<!DOCTYPE html>
<!-- saved from url=(0028)data:text/html,chromewebdata -->
<html i18n-values="dir:textdirection;lang:language" subframe="" dir="ltr" lang="zh" i18n-processed=""><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  
  <meta name="viewport" content="width=device-width, initial-scale=1.0,
                                 maximum-scale=1.0, user-scalable=no">
  <title i18n-content="title">log.51cto.com</title>
  <style>/* Copyright 2014 The Chromium Authors. All rights reserved.
   Use of this source code is governed by a BSD-style license that can be
   found in the LICENSE file. */

a {
  color: #585858;
}

.bad-clock .icon {
  background-image: -webkit-image-set(
      url() 1x,
      url() 2x);
}

body {
  background-color: #f7f7f7;
  color: #646464;
}

body.safe-browsing {
  background-color: rgb(206, 52, 38);
  color: white;
}

button {
  -webkit-user-select: none;
  background: rgb(66, 133, 244);
  border: 0;
  border-radius: 2px;
  box-sizing: border-box;
  color: #fff;
  cursor: pointer;
  float: right;
  font-size: .875em;
  margin: 0;
  padding: 10px 24px;
  transition: box-shadow 200ms cubic-bezier(0.4, 0, 0.2, 1);
}

[dir='rtl'] button {
  float: left;
}

button:active {
  background: rgb(50, 102, 213);
  outline: 0;
}

button:hover {
  box-shadow: 0 1px 3px rgba(0, 0, 0, .50);
}

#debugging {
  display: inline;
  overflow: auto;
}

.debugging-content {
  line-height: 1em;
  margin-bottom: 0;
  margin-top: 1em;
}

.debugging-content-fixed-width {
  display: block;
  font-family: monospace;
  font-size: 1.2em;
  margin-top: 0.5em;
}

.debugging-title {
  font-weight: bold;
}

#details {
  color: #696969;
  margin: 45px 0 50px;
}

#details p:not(:first-of-type) {
  margin-top: 20px;
}

#details-button {
  background: inherit;
  border: 0;
  float: none;
  margin: 0;
  padding: 10px 0;
  text-transform: uppercase;
}

#details-button:hover {
  box-shadow: inherit;
  text-decoration: underline;
}

.error-code {
  color: #646464;
  display: inline;
  font-size: .86667em;
  margin-top: 15px;
  opacity: 1;
  text-transform: uppercase;
}

#error-debugging-info {
  font-size: 0.8em;
}

h1 {
  color: #333;
  font-size: 1.6em;
  font-weight: normal;
  line-height: 1.25em;
  margin-bottom: 16px;
}

h2 {
  font-size: 1.2em;
  font-weight: normal;
}

.hidden {
  display: none;
}

html {
  -webkit-text-size-adjust: 100%;
  font-size: 125%;
}

.icon {
  background-repeat: no-repeat;
  background-size: 100%;
  height: 72px;
  margin: 0 0 40px;
  width: 72px;
}

input[type=checkbox] {
  opacity: 0;
}

input[type=checkbox]:focus ~ .checkbox {
  outline: -webkit-focus-ring-color auto 5px;
}

.interstitial-wrapper {
  box-sizing: border-box;
  font-size: 1em;
  line-height: 1.6em;
  margin: 100px auto 0;
  max-width: 600px;
  width: 100%;
}

#main-message > p {
  display: inline;
}

#extended-reporting-opt-in {
  font-size: .875em;
  margin-top: 39px;
}

#extended-reporting-opt-in label {
  position: relative;
  display: flex;
  align-items: flex-start;
}

.nav-wrapper {
  margin-top: 51px;
}

.nav-wrapper::after {
  clear: both;
  content: '';
  display: table;
  width: 100%;
}

.safe-browsing :-webkit-any(
    a, #details, #details-button, h1, h2, p, .small-link) {
  color: white;
}

.safe-browsing button {
  background-color: rgba(255, 255, 255, .15);
}

.safe-browsing button:active {
  background-color: rgba(255, 255, 255, .25);
}

.safe-browsing button:hover {
  box-shadow: 0 2px 3px rgba(0, 0, 0, .5);
}

.safe-browsing .error-code {
  display: none;
}

.safe-browsing .icon {
  background-image: -webkit-image-set(
      url() 1x,
      url() 2x);
}

.small-link {
  color: #696969;
  font-size: .875em;
}

.ssl .icon {
  background-image: -webkit-image-set(
      url() 1x,
      url() 2x);
}

.captive-portal .icon {
  background-image: -webkit-image-set(
      url() 1x,
      url() 2x);
}

.checkboxes {
  flex: 0 0 24px;
}

.checkbox {
  background: transparent;
  border: 1px solid white;
  border-radius: 2px;
  display: block;
  height: 14px;
  left: 0;
  position: absolute;
  right: 0;
  top: 3px;
  width: 14px;
}

.checkbox::before {
  background: transparent;
  border: 2px solid white;
  border-right-width: 0;
  border-top-width: 0;
  content: '';
  height: 4px;
  left: 2px;
  opacity: 0;
  position: absolute;
  top: 3px;
  transform: rotate(-45deg);
  width: 9px;
}

.ssl-opt-in .checkbox {
  border-color: #696969;
}

.ssl-opt-in .checkbox::before {
  border-color: #696969;
}

input[type=checkbox]:checked ~ .checkbox::before {
  opacity: 1;
}

@media (max-width: 700px) {
  .interstitial-wrapper {
    padding: 0 10%;
  }

  #error-debugging-info {
    overflow: auto;
  }
}

@media (max-height: 600px) {
  .error-code {
    margin-top: 10px;
  }
}

@media (max-width: 420px) {
  button,
  [dir='rtl'] button,
  .small-link {
    float: none;
    font-size: .825em;
    font-weight: 400;
    margin: 0;
    text-transform: uppercase;
    width: 100%;
  }

  #details {
    margin: 20px 0 20px 0;
  }

  #details p:not(:first-of-type) {
    margin-top: 10px;
  }

  #details-button {
    display: block;
    margin-top: 20px;
    text-align: center;
    width: 100%;
  }

  .interstitial-wrapper {
    padding: 0 5%;
  }

  #extended-reporting-opt-in {
    margin-top: 24px;
  }

  .nav-wrapper {
    margin-top: 30px;
  }
}

/**
 * Mobile specific styling.
 * Navigation buttons are anchored to the bottom of the screen.
 * Details message replaces the top content in its own scrollable area.
 */

@media (max-width: 420px) and (max-height: 736px) and (orientation: portrait) {
  #details-button {
    border: 0;
    margin: 8px 0 0;
  }

  .secondary-button {
    -webkit-margin-end: 0;
    margin-top: 16px;
  }
}

/* Fixed nav. */
@media (min-width: 240px) and (max-width: 420px) and
       (min-height: 401px) and (max-height: 736px) and (orientation:portrait),
       (min-width: 421px) and (max-width: 736px) and (min-height: 240px) and
       (max-height: 420px) and (orientation:landscape) {
  body .nav-wrapper {
    background: #f7f7f7;
    bottom: 0;
    box-shadow: 0 -22px 40px rgb(247, 247, 247);
    left: 0;
    margin: 0;
    max-width: 736px;
    padding-left: 24px;
    padding-right: 24px;
    position: fixed;
    z-index: 2;
  }

  body.safe-browsing .nav-wrapper {
    background: rgb(206, 52, 38);
    box-shadow: 0 -22px 40px rgb(206, 52, 38);
  }

  .interstitial-wrapper {
    max-width: 736px;
  }

  #details,
  #main-content {
    padding-bottom: 40px;
  }
}

@media (max-width: 420px) and (max-height: 736px) and (orientation: portrait),
       (max-width: 736px) and (max-height: 420px) and (orientation: landscape) {
  body {
    margin: 0 auto;
  }

  button,
  [dir='rtl'] button,
  button.small-link {
    font-family: Roboto-Regular,Helvetica;
    font-size: .933em;
    font-weight: 600;
    margin: 6px 0;
    text-transform: uppercase;
    transform: translatez(0);
  }

  .nav-wrapper {
    box-sizing: border-box;
    padding-bottom: 8px;
    width: 100%;
  }

  .error-code {
    margin-top: 0;
  }

  #details {
    box-sizing: border-box;
    height: auto;
    margin: 0;
    opacity: 1;
    transition: opacity 250ms cubic-bezier(0.4, 0, 0.2, 1);
  }

  #details.hidden,
  #main-content.hidden {
    display: block;
    height: 0;
    opacity: 0;
    overflow: hidden;
    transition: none;
  }

  #details-button {
    padding-bottom: 16px;
    padding-top: 16px;
  }

  h1 {
    font-size: 1.5em;
    margin-bottom: 8px;
  }

  .icon {
    margin-bottom: 12px;
  }

  .interstitial-wrapper {
    box-sizing: border-box;
    margin: 24px auto 12px;
    padding: 0 24px;
    position: relative;
  }

  .interstitial-wrapper p {
    font-size: .95em;
    line-height: 1.61em;
    margin-top: 8px;
  }

  #main-content {
    margin: 0;
    transition: opacity 100ms cubic-bezier(0.4, 0, 0.2, 1);
  }

  .small-link {
    border: 0;
  }

  .suggested-left > #control-buttons,
  .suggested-right > #control-buttons {
    float: none;
    margin: 0;
  }
}

@media (min-height: 400px) and (orientation:portrait) {
  .interstitial-wrapper {
    margin-bottom: 145px;
  }
}

@media (min-height: 299px) and (orientation:portrait) {
  .nav-wrapper {
    padding-bottom: 16px;
  }
}

@media (min-height: 405px) and (max-height: 736px) and
       (max-width: 420px) and (orientation:portrait) {
  .icon {
    margin-bottom: 24px;
  }

  .interstitial-wrapper {
    margin-top: 64px;
  }
}

@media (min-height: 480px) and (max-width: 420px) and
       (max-height: 736px) and (orientation: portrait),
       (min-height: 338px) and (max-height: 420px) and (max-width: 736px) and
       (orientation: landscape) {
  .icon {
    margin-bottom: 24px;
  }

  .nav-wrapper {
    padding-bottom: 24px;
  }
}

@media (min-height: 500px) and (max-width: 414px) and (orientation: portrait) {
  .interstitial-wrapper {
    margin-top: 96px;
  }
}

/* Phablet sizing */
@media (min-width: 375px) and (min-height: 641px) and (max-height: 736px) and
       (max-width: 414px) and (orientation: portrait) {
  button,
  [dir='rtl'] button,
  .small-link {
    font-size: 1em;
    padding-bottom: 12px;
    padding-top: 12px;
  }

  body:not(.offline) .icon {
    height: 80px;
    width: 80px;
  }

  #details-button {
    margin-top: 28px;
  }

  h1 {
    font-size: 1.7em;
  }

  .icon {
    margin-bottom: 28px;
  }

  .interstitial-wrapper {
    padding: 28px;
  }

  .interstitial-wrapper p {
    font-size: 1.05em;
  }

  .nav-wrapper {
    padding: 28px;
  }
}

@media (min-width: 420px) and (max-width: 736px) and
       (min-height: 240px) and (max-height: 298px) and
       (orientation:landscape) {
  body:not(.offline) .icon {
    height: 50px;
    width: 50px;
  }

  .icon {
    padding-top: 0;
  }

  .interstitial-wrapper {
    margin-top: 16px;
  }

  .nav-wrapper {
    padding: 0 24px 8px;
  }
}

@media (min-width: 420px) and (max-width: 736px) and
       (min-height: 240px) and (max-height: 420px) and
       (orientation:landscape) {
  #details-button {
    margin: 0;
  }

  .interstitial-wrapper {
    margin-bottom: 70px;
  }

  .nav-wrapper {
    margin-top: 0;
  }

  #extended-reporting-opt-in {
    margin-top: 0;
  }
}

/* Phablet landscape */
@media (min-width: 680px) and (max-height: 414px) {
  .interstitial-wrapper {
    margin: 24px auto;
  }

  .nav-wrapper {
    margin: 16px auto 0;
  }
}

@media (max-height: 240px) and (orientation: landscape),
       (max-height: 480px) and (orientation: portrait),
       (max-width: 419px) and (max-height: 323px) {
  body:not(.offline) .icon {
    height: 56px;
    width: 56px;
  }

  .icon {
    margin-bottom: 16px;
  }
}

/* Small mobile screens. No fixed nav. */
@media (max-height: 400px) and (orientation: portrait),
       (max-height: 239px) and (orientation: landscape),
       (max-width: 419px) and (max-height: 399px) {
  .interstitial-wrapper {
    display: flex;
    flex-direction: column;
    margin-bottom: 0;
  }

  #details {
    flex: 1 1 auto;
    order: 0;
  }

  #main-content {
    flex: 1 1 auto;
    order: 0;
  }

  .nav-wrapper {
    flex: 0 1 auto;
    margin-top: 8px;
    order: 1;
    padding-left: 0;
    padding-right: 0;
    position: relative;
    width: 100%;
  }
}

@media (max-width: 239px) and (orientation: portrait) {
  .nav-wrapper {
    padding-left: 0;
    padding-right: 0;
  }
}
</style>
  <style>/* Copyright 2013 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file. */

/* Don't use the main frame div when the error is in a subframe. */
html[subframe] #main-frame-error {
  display: none;
}

/* Don't use the subframe error div when the error is in a main frame. */
html:not([subframe]) #sub-frame-error {
  display: none;
}

#diagnose-button {
  -webkit-margin-start: 0;
  float: none;
  margin-bottom: 10px;
  margin-top: 20px;
}

h1 {
  margin-top: 0;
  word-wrap: break-word;
}

h1 span {
  font-weight: 500;
}

h2 {
  color: #666;
  font-size: 1.2em;
  font-weight: normal;
  margin: 10px 0;
}

a {
  color: rgb(17, 85, 204);
  text-decoration: none;
}

.icon {
  -webkit-user-select: none;
  display: inline-block;
}

.icon-generic {
  /**
   * Can't access chrome://theme/IDR_ERROR_NETWORK_GENERIC from an untrusted
   * renderer process, so embed the resource manually.
   */
  content: -webkit-image-set(
      url() 1x,
      url() 2x);
}

.icon-offline {
  content: -webkit-image-set(
      url() 1x,
      url() 2x);
  position: relative;
}

.icon-disabled {
  content: -webkit-image-set(
      url() 1x,
      url() 2x);
  width: 112px;
}

.error-code {
  display: block;
  font-size: .8em;
}

#content-top {
  margin: 20px;
}

#help-box-inner {
  background-color: #f9f9f9;
  border-top: 1px solid #EEE;
  color: #444;
  padding: 20px;
  text-align: start;
}

.hidden {
  display: none;
}

#suggestion {
  margin-top: 15px;
}

#suggestions-list p {
  -webkit-margin-after: 0;
}

#suggestions-list ul {
  margin-top: 0;
}

.single-suggestion {
  list-style-type: none;
  padding-left: 0;
}

#short-suggestion {
  margin-top: 5px;
}

#sub-frame-error-details {

  color: #8F8F8F;

  /* Not done on mobile for performance reasons. */
  text-shadow: 0 1px 0 rgba(255,255,255,0.3);

}

[jscontent=hostName],
[jscontent=failedUrl] {
  overflow-wrap: break-word;
}

#search-container {
  /* Prevents a space between controls. */
  display: flex;
  margin-top: 20px;
}

#search-box {
  border: 1px solid #cdcdcd;
  flex-grow: 1;
  font-size: 1em;
  height: 26px;
  margin-right: 0;
  padding: 1px 9px;
}

#search-box:focus {
  border: 1px solid rgb(93, 154, 255);
  outline: none;
}

#search-button {
  border: none;
  border-bottom-left-radius: 0;
  border-top-left-radius: 0;
  box-shadow: none;
  display: flex;
  height: 30px;
  margin: 0;
  padding: 0;
  width: 60px;
}

#search-image {
  content:
      -webkit-image-set(
          url() 1x,
          url() 2x);
  margin: auto;
}

.secondary-button {
  -webkit-margin-end: 16px;
  background: #d9d9d9;
  color: #696969;
}

.snackbar {
  background: #323232;
  border-radius: 2px;
  bottom: 24px;
  box-sizing: border-box;
  color: #fff;
  font-size: .87em;
  left: 24px;
  max-width: 568px;
  min-width: 288px;
  opacity: 0;
  padding: 16px 24px 12px;
  position: fixed;
  transform: translateY(90px);
  will-change: opacity, transform;
  z-index: 999;
}

.snackbar-show {
  -webkit-animation:
    show-snackbar .25s cubic-bezier(0.0, 0.0, 0.2, 1) forwards,
    hide-snackbar .25s cubic-bezier(0.4, 0.0, 1, 1) forwards 5s;
}

@-webkit-keyframes show-snackbar {
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}

@-webkit-keyframes hide-snackbar {
  0% {
    opacity: 1;
    transform: translateY(0);
  }
  100% {
    opacity: 0;
    transform: translateY(90px);
  }
}

.suggestions {
  margin-top: 18px;
}

.suggestion-header {
  font-weight: bold;
  margin-bottom: 4px;
}

.suggestion-body {
  color: #777;
}

/* Increase line height at higher resolutions. */
@media (min-width: 641px) and (min-height: 641px) {
  #help-box-inner {
    line-height: 18px;
  }
}

/* Decrease padding at low sizes. */
@media (max-width: 640px), (max-height: 640px) {
  h1 {
    margin: 0 0 15px;
  }
  #content-top {
    margin: 15px;
  }
  #help-box-inner {
    padding: 20px;
  }
  .suggestions {
    margin-top: 10px;
  }
  .suggestion-header {
    margin-bottom: 0;
  }
}

/* Don't allow overflow when in a subframe. */
html[subframe] body {
  overflow: hidden;
}

#sub-frame-error {
  -webkit-align-items: center;
  background-color: #DDD;
  display: -webkit-flex;
  -webkit-flex-flow: column;
  height: 100%;
  -webkit-justify-content: center;
  left: 0;
  position: absolute;
  text-align: center;
  top: 0;
  transition: background-color .2s ease-in-out;
  width: 100%;
}

#sub-frame-error:hover {
  background-color: #EEE;
}

#sub-frame-error .icon-generic {
  margin: 0 0 16px;
}

#sub-frame-error-details {
  margin: 0 10px;
  text-align: center;
  visibility: hidden;
}

/* Show details only when hovering. */
#sub-frame-error:hover #sub-frame-error-details {
  visibility: visible;
}

/* If the iframe is too small, always hide the error code. */
/* TODO(mmenke): See if overflow: no-display works better, once supported. */
@media (max-width: 200px), (max-height: 95px) {
  #sub-frame-error-details {
    display: none;
  }
}

/* Adjust icon for small embedded frames in apps. */
@media (max-height: 100px) {
  #sub-frame-error .icon-generic {
    height: auto;
    margin: 0;
    padding-top: 0;
    width: 25px;
  }
}

/* details-button is special; it's a <button> element that looks like a link. */
#details-button {
  box-shadow: none;
  min-width: 0;
}

/* Styles for platform dependent separation of controls and details button. */
.suggested-left > #control-buttons,
.suggested-left #stale-load-button,
.suggested-right > #details-button {
  float: left;
}

.suggested-right > #control-buttons,
.suggested-right #stale-load-button,
.suggested-left > #details-button {
  float: right;
}

.suggested-left .secondary-button {
  -webkit-margin-end: 0px;
  -webkit-margin-start: 16px;
}

#details-button.singular {
  float: none;
}

/* download-button shows both icon and text. */
#download-button {
  box-shadow: none;
  position: relative;
}

#download-button:before {
  -webkit-margin-end: 4px;
  background: -webkit-image-set(
      url() 1x,
      url() 2x)
    no-repeat;
  content: '';
  display: inline-block;
  width: 24px;
  height: 24px;
  vertical-align: middle;
}

#download-button:disabled {
  background: rgb(180, 206, 249);
  color: rgb(255, 255, 255);
}

#buttons::after {
  clear: both;
  content: '';
  display: block;
  width: 100%;
}

/* Offline page */
.offline {
  transition: -webkit-filter 1.5s cubic-bezier(0.65, 0.05, 0.36, 1),
              background-color 1.5s cubic-bezier(0.65, 0.05, 0.36, 1);
  will-change: -webkit-filter, background-color;
}

.offline #main-message > p {
  display: none;
}

.offline.inverted {
  -webkit-filter: invert(100%);
  background-color: #000;
}

.offline .interstitial-wrapper {
  color: #2b2b2b;
  font-size: 1em;
  line-height: 1.55;
  margin: 0 auto;
  max-width: 600px;
  padding-top: 100px;
  width: 100%;
}

.offline .runner-container {
  direction: ltr;
  height: 150px;
  max-width: 600px;
  overflow: hidden;
  position: absolute;
  top: 35px;
  width: 44px;
}

.offline .runner-canvas {
  height: 150px;
  max-width: 600px;
  opacity: 1;
  overflow: hidden;
  position: absolute;
  top: 0;
  z-index: 2;
}

.offline .controller {
  background: rgba(247,247,247, .1);
  height: 100vh;
  left: 0;
  position: absolute;
  top: 0;
  width: 100vw;
  z-index: 1;
}

#offline-resources {
  display: none;
}

@media (max-width: 420px) {
  .suggested-left > #control-buttons,
  .suggested-right > #control-buttons {
    float: none;
  }

  .snackbar {
    left: 0;
    bottom: 0;
    width: 100%;
    border-radius: 0;
  }
}

@media (max-height: 350px) {
  h1 {
    margin: 0 0 15px;
  }

  .icon-offline {
    margin: 0 0 10px;
  }

  .interstitial-wrapper {
    margin-top: 5%;
  }

  .nav-wrapper {
    margin-top: 30px;
  }
}

@media (min-width: 600px) and (max-width: 736px) and (orientation: landscape) {
  .offline .interstitial-wrapper {
    margin-left: 0;
    margin-right: 0;
  }
}

@media (min-width: 420px) and (max-width: 736px) and
       (min-height: 240px) and (max-height: 420px) and
       (orientation:landscape) {
  .interstitial-wrapper {
    margin-bottom: 100px;
  }
}

@media (min-height: 240px) and (orientation: landscape) {
  .offline .interstitial-wrapper {
    margin-bottom: 90px;
  }

  .icon-offline {
    margin-bottom: 20px;
  }
}

@media (max-height: 320px) and (orientation: landscape) {
  .icon-offline {
    margin-bottom: 0;
  }

  .offline .runner-container {
    top: 10px;
  }
}

@media (max-width: 240px) {
  button {
    padding-left: 12px;
    padding-right: 12px;
  }

  .interstitial-wrapper {
    overflow: inherit;
    padding: 0 8px;
  }
}

@media (max-width: 120px) {
  button {
    width: auto;
  }
}
</style>
  <script>// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

var mobileNav = false;

/**
 * For small screen mobile the navigation buttons are moved
 * below the advanced text.
 */
function onResize() {
  var helpOuterBox = document.querySelector('#details');
  var mainContent = document.querySelector('#main-content');
  var mediaQuery = '(min-width: 240px) and (max-width: 420px) and ' +
      '(max-height: 736px) and (min-height: 401px) and ' +
      '(orientation: portrait), (max-width: 736px) and ' +
      '(max-height: 420px) and (min-height: 240px) and ' +
      '(min-width: 421px) and (orientation: landscape)';

  var detailsHidden = helpOuterBox.classList.contains('hidden');
  var runnerContainer = document.querySelector('.runner-container');

  // Check for change in nav status.
  if (mobileNav != window.matchMedia(mediaQuery).matches) {
    mobileNav = !mobileNav;

    // Handle showing the top content / details sections according to state.
    if (mobileNav) {
      mainContent.classList.toggle('hidden', !detailsHidden);
      helpOuterBox.classList.toggle('hidden', detailsHidden);
      if (runnerContainer) {
        runnerContainer.classList.toggle('hidden', !detailsHidden);
      }
    } else if (!detailsHidden) {
      // Non mobile nav with visible details.
      mainContent.classList.remove('hidden');
      helpOuterBox.classList.remove('hidden');
      if (runnerContainer) {
        runnerContainer.classList.remove('hidden');
      }
    }
  }
}

function setupMobileNav() {
  window.addEventListener('resize', onResize);
  onResize();
}

document.addEventListener('DOMContentLoaded', setupMobileNav);
</script>
  <script>// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

function toggleHelpBox() {
  var helpBoxOuter = document.getElementById('details');
  helpBoxOuter.classList.toggle('hidden');
  var detailsButton = document.getElementById('details-button');
  if (helpBoxOuter.classList.contains('hidden'))
    detailsButton.innerText = detailsButton.detailsText;
  else
    detailsButton.innerText = detailsButton.hideDetailsText;

  // Details appears over the main content on small screens.
  if (mobileNav) {
    document.getElementById('main-content').classList.toggle('hidden');
    var runnerContainer = document.querySelector('.runner-container');
    if (runnerContainer) {
      runnerContainer.classList.toggle('hidden');
    }
  }
}

function diagnoseErrors() {
// 
    if (window.errorPageController)
      errorPageController.diagnoseErrorsButtonClick();
// 
// 
}

// Subframes use a different layout but the same html file.  This is to make it
// easier to support platforms that load the error page via different
// mechanisms (Currently just iOS).
if (window.top.location != window.location)
  document.documentElement.setAttribute('subframe', '');

// Re-renders the error page using |strings| as the dictionary of values.
// Used by NetErrorTabHelper to update DNS error pages with probe results.
function updateForDnsProbe(strings) {
  var context = new JsEvalContext(strings);
  jstProcess(context, document.getElementById('t'));
}

// Given the classList property of an element, adds an icon class to the list
// and removes the previously-
function updateIconClass(classList, newClass) {
  var oldClass;

  if (classList.hasOwnProperty('last_icon_class')) {
    oldClass = classList['last_icon_class'];
    if (oldClass == newClass)
      return;
  }

  classList.add(newClass);
  if (oldClass !== undefined)
    classList.remove(oldClass);

  classList['last_icon_class'] = newClass;

  if (newClass == 'icon-offline') {
    document.body.classList.add('offline');
    new Runner('.interstitial-wrapper');
  } else {
    document.body.classList.add('neterror');
  }
}

// Does a search using |baseSearchUrl| and the text in the search box.
function search(baseSearchUrl) {
  var searchTextNode = document.getElementById('search-box');
  document.location = baseSearchUrl + searchTextNode.value;
  return false;
}

// Use to track clicks on elements generated by the navigation correction
// service.  If |trackingId| is negative, the element does not come from the
// correction service.
function trackClick(trackingId) {
  // This can't be done with XHRs because XHRs are cancelled on navigation
  // start, and because these are cross-site requests.
  if (trackingId >= 0 && errorPageController)
    errorPageController.trackClick(trackingId);
}

// Called when an <a> tag generated by the navigation correction service is
// clicked.  Separate function from trackClick so the resources don't have to
// be updated if new data is added to jstdata.
function linkClicked(jstdata) {
  trackClick(jstdata.trackingId);
}

// Implements button clicks.  This function is needed during the transition
// between implementing these in trunk chromium and implementing them in
// iOS.
function reloadButtonClick(url) {
  if (window.errorPageController) {
    errorPageController.reloadButtonClick();
  } else {
    location = url;
  }
}

function showSavedCopyButtonClick() {
  if (window.errorPageController) {
    errorPageController.showSavedCopyButtonClick();
  }
}

function downloadButtonClick() {
  if (window.errorPageController) {
    errorPageController.downloadButtonClick();
    var downloadButton = document.getElementById('download-button');
    downloadButton.disabled = true;
    downloadButton.textContent = downloadButton.disabledText;
  }
}

function detailsButtonClick() {
  if (window.errorPageController)
    errorPageController.detailsButtonClick();
}

/**
 * Replace the reload button with the Google cached copy suggestion.
 */
function setUpCachedButton(buttonStrings) {
  var reloadButton = document.getElementById('reload-button');

  reloadButton.textContent = buttonStrings.msg;
  var url = buttonStrings.cacheUrl;
  var trackingId = buttonStrings.trackingId;
  reloadButton.onclick = function(e) {
    e.preventDefault();
    trackClick(trackingId);
    if (window.errorPageController) {
      errorPageController.trackCachedCopyButtonClick();
    }
    location = url;
  };
  reloadButton.style.display = '';
  document.getElementById('control-buttons').hidden = false;
}

var primaryControlOnLeft = true;
// 
primaryControlOnLeft = false;
// 

function onDocumentLoad() {
  var controlButtonDiv = document.getElementById('control-buttons');
  var reloadButton = document.getElementById('reload-button');
  var detailsButton = document.getElementById('details-button');
  var showSavedCopyButton = document.getElementById('show-saved-copy-button');
  var downloadButton = document.getElementById('download-button');

  var reloadButtonVisible = loadTimeData.valueExists('reloadButton') &&
      loadTimeData.getValue('reloadButton').msg;
  var showSavedCopyButtonVisible =
      loadTimeData.valueExists('showSavedCopyButton') &&
      loadTimeData.getValue('showSavedCopyButton').msg;
  var downloadButtonVisible =
      loadTimeData.valueExists('downloadButton') &&
      loadTimeData.getValue('downloadButton').msg;

  var primaryButton, secondaryButton;
  if (showSavedCopyButton.primary) {
    primaryButton = showSavedCopyButton;
    secondaryButton = reloadButton;
  } else {
    primaryButton = reloadButton;
    secondaryButton = showSavedCopyButton;
  }

  // Sets up the proper button layout for the current platform.
  if (primaryControlOnLeft) {
    buttons.classList.add('suggested-left');
    controlButtonDiv.insertBefore(secondaryButton, primaryButton);
  } else {
    buttons.classList.add('suggested-right');
    controlButtonDiv.insertBefore(primaryButton, secondaryButton);
  }

  // Check for Google cached copy suggestion.
  if (loadTimeData.valueExists('cacheButton')) {
    setUpCachedButton(loadTimeData.getValue('cacheButton'));
  }

  if (reloadButton.style.display == 'none' &&
      showSavedCopyButton.style.display == 'none' &&
      downloadButton.style.display == 'none') {
    detailsButton.classList.add('singular');
  }

  // Show control buttons.
  if (reloadButtonVisible || showSavedCopyButtonVisible ||
      downloadButtonVisible) {
    controlButtonDiv.hidden = false;

    // Set the secondary button state in the cases of two call to actions.
    if ((reloadButtonVisible || downloadButtonVisible) &&
        showSavedCopyButtonVisible) {
      secondaryButton.classList.add('secondary-button');
    }
  }
}

document.addEventListener('DOMContentLoaded', onDocumentLoad);
</script>
  <script>// Copyright (c) 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
(function() {
'use strict';
/**
 * T-Rex runner.
 * @param {string} outerContainerId Outer containing element id.
 * @param {Object} opt_config
 * @constructor
 * @export
 */
function Runner(outerContainerId, opt_config) {
  // Singleton
  if (Runner.instance_) {
    return Runner.instance_;
  }
  Runner.instance_ = this;

  this.outerContainerEl = document.querySelector(outerContainerId);
  this.containerEl = null;
  this.snackbarEl = null;

  this.config = opt_config || Runner.config;

  this.dimensions = Runner.defaultDimensions;

  this.canvas = null;
  this.canvasCtx = null;

  this.tRex = null;

  this.distanceMeter = null;
  this.distanceRan = 0;

  this.highestScore = 0;

  this.time = 0;
  this.runningTime = 0;
  this.msPerFrame = 1000 / FPS;
  this.currentSpeed = this.config.SPEED;

  this.obstacles = [];

  this.activated = false; // Whether the easter egg has been activated.
  this.playing = false; // Whether the game is currently in play state.
  this.crashed = false;
  this.paused = false;
  this.inverted = false;
  this.invertTimer = 0;
  this.resizeTimerId_ = null;

  this.playCount = 0;

  // Sound FX.
  this.audioBuffer = null;
  this.soundFx = {};

  // Global web audio context for playing sounds.
  this.audioContext = null;

  // Images.
  this.images = {};
  this.imagesLoaded = 0;

  if (this.isDisabled()) {
    this.setupDisabledRunner();
  } else {
    this.loadImages();
  }
}
window['Runner'] = Runner;


/**
 * Default game width.
 * @const
 */
var DEFAULT_WIDTH = 600;

/**
 * Frames per second.
 * @const
 */
var FPS = 60;

/** @const */
var IS_HIDPI = window.devicePixelRatio > 1;

/** @const */
var IS_IOS = /iPad|iPhone|iPod/.test(window.navigator.platform);

/** @const */
var IS_MOBILE = /Android/.test(window.navigator.userAgent) || IS_IOS;

/** @const */
var IS_TOUCH_ENABLED = 'ontouchstart' in window;

/**
 * Default game configuration.
 * @enum {number}
 */
Runner.config = {
  ACCELERATION: 0.001,
  BG_CLOUD_SPEED: 0.2,
  BOTTOM_PAD: 10,
  CLEAR_TIME: 3000,
  CLOUD_FREQUENCY: 0.5,
  GAMEOVER_CLEAR_TIME: 750,
  GAP_COEFFICIENT: 0.6,
  GRAVITY: 0.6,
  INITIAL_JUMP_VELOCITY: 12,
  INVERT_FADE_DURATION: 12000,
  INVERT_DISTANCE: 700,
  MAX_BLINK_COUNT: 3,
  MAX_CLOUDS: 6,
  MAX_OBSTACLE_LENGTH: 3,
  MAX_OBSTACLE_DUPLICATION: 2,
  MAX_SPEED: 13,
  MIN_JUMP_HEIGHT: 35,
  MOBILE_SPEED_COEFFICIENT: 1.2,
  RESOURCE_TEMPLATE_ID: 'audio-resources',
  SPEED: 6,
  SPEED_DROP_COEFFICIENT: 3
};


/**
 * Default dimensions.
 * @enum {string}
 */
Runner.defaultDimensions = {
  WIDTH: DEFAULT_WIDTH,
  HEIGHT: 150
};


/**
 * CSS class names.
 * @enum {string}
 */
Runner.classes = {
  CANVAS: 'runner-canvas',
  CONTAINER: 'runner-container',
  CRASHED: 'crashed',
  ICON: 'icon-offline',
  INVERTED: 'inverted',
  SNACKBAR: 'snackbar',
  SNACKBAR_SHOW: 'snackbar-show',
  TOUCH_CONTROLLER: 'controller'
};


/**
 * Sprite definition layout of the spritesheet.
 * @enum {Object}
 */
Runner.spriteDefinition = {
  LDPI: {
    CACTUS_LARGE: {x: 332, y: 2},
    CACTUS_SMALL: {x: 228, y: 2},
    CLOUD: {x: 86, y: 2},
    HORIZON: {x: 2, y: 54},
    MOON: {x: 484, y: 2},
    PTERODACTYL: {x: 134, y: 2},
    RESTART: {x: 2, y: 2},
    TEXT_SPRITE: {x: 655, y: 2},
    TREX: {x: 848, y: 2},
    STAR: {x: 645, y: 2}
  },
  HDPI: {
    CACTUS_LARGE: {x: 652, y: 2},
    CACTUS_SMALL: {x: 446, y: 2},
    CLOUD: {x: 166, y: 2},
    HORIZON: {x: 2, y: 104},
    MOON: {x: 954, y: 2},
    PTERODACTYL: {x: 260, y: 2},
    RESTART: {x: 2, y: 2},
    TEXT_SPRITE: {x: 1294, y: 2},
    TREX: {x: 1678, y: 2},
    STAR: {x: 1276, y: 2}
  }
};


/**
 * Sound FX. Reference to the ID of the audio tag on interstitial page.
 * @enum {string}
 */
Runner.sounds = {
  BUTTON_PRESS: 'offline-sound-press',
  HIT: 'offline-sound-hit',
  SCORE: 'offline-sound-reached'
};


/**
 * Key code mapping.
 * @enum {Object}
 */
Runner.keycodes = {
  JUMP: {'38': 1, '32': 1},  // Up, spacebar
  DUCK: {'40': 1},  // Down
  RESTART: {'13': 1}  // Enter
};


/**
 * Runner event names.
 * @enum {string}
 */
Runner.events = {
  ANIM_END: 'webkitAnimationEnd',
  CLICK: 'click',
  KEYDOWN: 'keydown',
  KEYUP: 'keyup',
  MOUSEDOWN: 'mousedown',
  MOUSEUP: 'mouseup',
  RESIZE: 'resize',
  TOUCHEND: 'touchend',
  TOUCHSTART: 'touchstart',
  VISIBILITY: 'visibilitychange',
  BLUR: 'blur',
  FOCUS: 'focus',
  LOAD: 'load'
};


Runner.prototype = {
  /**
   * Whether the easter egg has been disabled. CrOS enterprise enrolled devices.
   * @return {boolean}
   */
  isDisabled: function() {
    return loadTimeData && loadTimeData.valueExists('disabledEasterEgg');
  },

  /**
   * For disabled instances, set up a snackbar with the disabled message.
   */
  setupDisabledRunner: function() {
    this.containerEl = document.createElement('div');
    this.containerEl.className = Runner.classes.SNACKBAR;
    this.containerEl.textContent = loadTimeData.getValue('disabledEasterEgg');
    this.outerContainerEl.appendChild(this.containerEl);

    // Show notification when the activation key is pressed.
    document.addEventListener(Runner.events.KEYDOWN, function(e) {
      if (Runner.keycodes.JUMP[e.keyCode]) {
        this.containerEl.classList.add(Runner.classes.SNACKBAR_SHOW);
        document.querySelector('.icon').classList.add('icon-disabled');
      }
    }.bind(this));
  },

  /**
   * Setting individual settings for debugging.
   * @param {string} setting
   * @param {*} value
   */
  updateConfigSetting: function(setting, value) {
    if (setting in this.config && value != undefined) {
      this.config[setting] = value;

      switch (setting) {
        case 'GRAVITY':
        case 'MIN_JUMP_HEIGHT':
        case 'SPEED_DROP_COEFFICIENT':
          this.tRex.config[setting] = value;
          break;
        case 'INITIAL_JUMP_VELOCITY':
          this.tRex.setJumpVelocity(value);
          break;
        case 'SPEED':
          this.setSpeed(value);
          break;
      }
    }
  },

  /**
   * Cache the appropriate image sprite from the page and get the sprite sheet
   * definition.
   */
  loadImages: function() {
    if (IS_HIDPI) {
      Runner.imageSprite = document.getElementById('offline-resources-2x');
      this.spriteDef = Runner.spriteDefinition.HDPI;
    } else {
      Runner.imageSprite = document.getElementById('offline-resources-1x');
      this.spriteDef = Runner.spriteDefinition.LDPI;
    }

    if (Runner.imageSprite.complete) {
      this.init();
    } else {
      // If the images are not yet loaded, add a listener.
      Runner.imageSprite.addEventListener(Runner.events.LOAD,
          this.init.bind(this));
    }
  },

  /**
   * Load and decode base 64 encoded sounds.
   */
  loadSounds: function() {
    if (!IS_IOS) {
      this.audioContext = new AudioContext();

      var resourceTemplate =
          document.getElementById(this.config.RESOURCE_TEMPLATE_ID).content;

      for (var sound in Runner.sounds) {
        var soundSrc =
            resourceTemplate.getElementById(Runner.sounds[sound]).src;
        soundSrc = soundSrc.substr(soundSrc.indexOf(',') + 1);
        var buffer = decodeBase64ToArrayBuffer(soundSrc);

        // Async, so no guarantee of order in array.
        this.audioContext.decodeAudioData(buffer, function(index, audioData) {
            this.soundFx[index] = audioData;
          }.bind(this, sound));
      }
    }
  },

  /**
   * Sets the game speed. Adjust the speed accordingly if on a smaller screen.
   * @param {number} opt_speed
   */
  setSpeed: function(opt_speed) {
    var speed = opt_speed || this.currentSpeed;

    // Reduce the speed on smaller mobile screens.
    if (this.dimensions.WIDTH < DEFAULT_WIDTH) {
      var mobileSpeed = speed * this.dimensions.WIDTH / DEFAULT_WIDTH *
          this.config.MOBILE_SPEED_COEFFICIENT;
      this.currentSpeed = mobileSpeed > speed ? speed : mobileSpeed;
    } else if (opt_speed) {
      this.currentSpeed = opt_speed;
    }
  },

  /**
   * Game initialiser.
   */
  init: function() {
    // Hide the static icon.
    document.querySelector('.' + Runner.classes.ICON).style.visibility =
        'hidden';

    this.adjustDimensions();
    this.setSpeed();

    this.containerEl = document.createElement('div');
    this.containerEl.className = Runner.classes.CONTAINER;

    // Player canvas container.
    this.canvas = createCanvas(this.containerEl, this.dimensions.WIDTH,
        this.dimensions.HEIGHT, Runner.classes.PLAYER);

    this.canvasCtx = this.canvas.getContext('2d');
    this.canvasCtx.fillStyle = '#f7f7f7';
    this.canvasCtx.fill();
    Runner.updateCanvasScaling(this.canvas);

    // Horizon contains clouds, obstacles and the ground.
    this.horizon = new Horizon(this.canvas, this.spriteDef, this.dimensions,
        this.config.GAP_COEFFICIENT);

    // Distance meter
    this.distanceMeter = new DistanceMeter(this.canvas,
          this.spriteDef.TEXT_SPRITE, this.dimensions.WIDTH);

    // Draw t-rex
    this.tRex = new Trex(this.canvas, this.spriteDef.TREX);

    this.outerContainerEl.appendChild(this.containerEl);

    if (IS_MOBILE) {
      this.createTouchController();
    }

    this.startListening();
    this.update();

    window.addEventListener(Runner.events.RESIZE,
        this.debounceResize.bind(this));
  },

  /**
   * Create the touch controller. A div that covers whole screen.
   */
  createTouchController: function() {
    this.touchController = document.createElement('div');
    this.touchController.className = Runner.classes.TOUCH_CONTROLLER;
  },

  /**
   * Debounce the resize event.
   */
  debounceResize: function() {
    if (!this.resizeTimerId_) {
      this.resizeTimerId_ =
          setInterval(this.adjustDimensions.bind(this), 250);
    }
  },

  /**
   * Adjust game space dimensions on resize.
   */
  adjustDimensions: function() {
    clearInterval(this.resizeTimerId_);
    this.resizeTimerId_ = null;

    var boxStyles = window.getComputedStyle(this.outerContainerEl);
    var padding = Number(boxStyles.paddingLeft.substr(0,
        boxStyles.paddingLeft.length - 2));

    this.dimensions.WIDTH = this.outerContainerEl.offsetWidth - padding * 2;

    // Redraw the elements back onto the canvas.
    if (this.canvas) {
      this.canvas.width = this.dimensions.WIDTH;
      this.canvas.height = this.dimensions.HEIGHT;

      Runner.updateCanvasScaling(this.canvas);

      this.distanceMeter.calcXPos(this.dimensions.WIDTH);
      this.clearCanvas();
      this.horizon.update(0, 0, true);
      this.tRex.update(0);

      // Outer container and distance meter.
      if (this.playing || this.crashed || this.paused) {
        this.containerEl.style.width = this.dimensions.WIDTH + 'px';
        this.containerEl.style.height = this.dimensions.HEIGHT + 'px';
        this.distanceMeter.update(0, Math.ceil(this.distanceRan));
        this.stop();
      } else {
        this.tRex.draw(0, 0);
      }

      // Game over panel.
      if (this.crashed && this.gameOverPanel) {
        this.gameOverPanel.updateDimensions(this.dimensions.WIDTH);
        this.gameOverPanel.draw();
      }
    }
  },

  /**
   * Play the game intro.
   * Canvas container width expands out to the full width.
   */
  playIntro: function() {
    if (!this.activated && !this.crashed) {
      this.playingIntro = true;
      this.tRex.playingIntro = true;

      // CSS animation definition.
      var keyframes = '@-webkit-keyframes intro { ' +
            'from { width:' + Trex.config.WIDTH + 'px }' +
            'to { width: ' + this.dimensions.WIDTH + 'px }' +
          '}';
      document.styleSheets[0].insertRule(keyframes, 0);

      this.containerEl.addEventListener(Runner.events.ANIM_END,
          this.startGame.bind(this));

      this.containerEl.style.webkitAnimation = 'intro .4s ease-out 1 both';
      this.containerEl.style.width = this.dimensions.WIDTH + 'px';

      if (this.touchController) {
        this.outerContainerEl.appendChild(this.touchController);
      }
      this.playing = true;
      this.activated = true;
    } else if (this.crashed) {
      this.restart();
    }
  },


  /**
   * Update the game status to started.
   */
  startGame: function() {
    this.runningTime = 0;
    this.playingIntro = false;
    this.tRex.playingIntro = false;
    this.containerEl.style.webkitAnimation = '';
    this.playCount++;

    // Handle tabbing off the page. Pause the current game.
    document.addEventListener(Runner.events.VISIBILITY,
          this.onVisibilityChange.bind(this));

    window.addEventListener(Runner.events.BLUR,
          this.onVisibilityChange.bind(this));

    window.addEventListener(Runner.events.FOCUS,
          this.onVisibilityChange.bind(this));
  },

  clearCanvas: function() {
    this.canvasCtx.clearRect(0, 0, this.dimensions.WIDTH,
        this.dimensions.HEIGHT);
  },

  /**
   * Update the game frame and schedules the next one.
   */
  update: function() {
    this.updatePending = false;

    var now = getTimeStamp();
    var deltaTime = now - (this.time || now);
    this.time = now;

    if (this.playing) {
      this.clearCanvas();

      if (this.tRex.jumping) {
        this.tRex.updateJump(deltaTime);
      }

      this.runningTime += deltaTime;
      var hasObstacles = this.runningTime > this.config.CLEAR_TIME;

      // First jump triggers the intro.
      if (this.tRex.jumpCount == 1 && !this.playingIntro) {
        this.playIntro();
      }

      // The horizon doesn't move until the intro is over.
      if (this.playingIntro) {
        this.horizon.update(0, this.currentSpeed, hasObstacles);
      } else {
        deltaTime = !this.activated ? 0 : deltaTime;
        this.horizon.update(deltaTime, this.currentSpeed, hasObstacles,
            this.inverted);
      }

      // Check for collisions.
      var collision = hasObstacles &&
          checkForCollision(this.horizon.obstacles[0], this.tRex);

      if (!collision) {
        this.distanceRan += this.currentSpeed * deltaTime / this.msPerFrame;

        if (this.currentSpeed < this.config.MAX_SPEED) {
          this.currentSpeed += this.config.ACCELERATION;
        }
      } else {
        this.gameOver();
      }

      var playAchievementSound = this.distanceMeter.update(deltaTime,
          Math.ceil(this.distanceRan));

      if (playAchievementSound) {
        this.playSound(this.soundFx.SCORE);
      }

      // Night mode.
      if (this.invertTimer > this.config.INVERT_FADE_DURATION) {
        this.invertTimer = 0;
        this.invertTrigger = false;
        this.invert();
      } else if (this.invertTimer) {
        this.invertTimer += deltaTime;
      } else {
        var actualDistance =
            this.distanceMeter.getActualDistance(Math.ceil(this.distanceRan));

        if (actualDistance > 0) {
          this.invertTrigger = !(actualDistance %
              this.config.INVERT_DISTANCE);

          if (this.invertTrigger && this.invertTimer === 0) {
            this.invertTimer += deltaTime;
            this.invert();
          }
        }
      }
    }

    if (this.playing || (!this.activated &&
        this.tRex.blinkCount < Runner.config.MAX_BLINK_COUNT)) {
      this.tRex.update(deltaTime);
      this.scheduleNextUpdate();
    }
  },

  /**
   * Event handler.
   */
  handleEvent: function(e) {
    return (function(evtType, events) {
      switch (evtType) {
        case events.KEYDOWN:
        case events.TOUCHSTART:
        case events.MOUSEDOWN:
          this.onKeyDown(e);
          break;
        case events.KEYUP:
        case events.TOUCHEND:
        case events.MOUSEUP:
          this.onKeyUp(e);
          break;
      }
    }.bind(this))(e.type, Runner.events);
  },

  /**
   * Bind relevant key / mouse / touch listeners.
   */
  startListening: function() {
    // Keys.
    document.addEventListener(Runner.events.KEYDOWN, this);
    document.addEventListener(Runner.events.KEYUP, this);

    if (IS_MOBILE) {
      // Mobile only touch devices.
      this.touchController.addEventListener(Runner.events.TOUCHSTART, this);
      this.touchController.addEventListener(Runner.events.TOUCHEND, this);
      this.containerEl.addEventListener(Runner.events.TOUCHSTART, this);
    } else {
      // Mouse.
      document.addEventListener(Runner.events.MOUSEDOWN, this);
      document.addEventListener(Runner.events.MOUSEUP, this);
    }
  },

  /**
   * Remove all listeners.
   */
  stopListening: function() {
    document.removeEventListener(Runner.events.KEYDOWN, this);
    document.removeEventListener(Runner.events.KEYUP, this);

    if (IS_MOBILE) {
      this.touchController.removeEventListener(Runner.events.TOUCHSTART, this);
      this.touchController.removeEventListener(Runner.events.TOUCHEND, this);
      this.containerEl.removeEventListener(Runner.events.TOUCHSTART, this);
    } else {
      document.removeEventListener(Runner.events.MOUSEDOWN, this);
      document.removeEventListener(Runner.events.MOUSEUP, this);
    }
  },

  /**
   * Process keydown.
   * @param {Event} e
   */
  onKeyDown: function(e) {
    // Prevent native page scrolling whilst tapping on mobile.
    if (IS_MOBILE && this.playing) {
      e.preventDefault();
    }

    if (!this.crashed && !this.paused) {
      if (Runner.keycodes.JUMP[e.keyCode] ||
          e.type == Runner.events.TOUCHSTART) {
        e.preventDefault();
        // Starting the game for the first time.
        if (!this.playing) {
          this.loadSounds();
          this.playing = true;
          this.update();
          if (window.errorPageController) {
            errorPageController.trackEasterEgg();
          }
        }
        // Start jump.
        if (!this.tRex.jumping && !this.tRex.ducking) {
          this.playSound(this.soundFx.BUTTON_PRESS);
          this.tRex.startJump(this.currentSpeed);
        }
      } else if (this.playing && Runner.keycodes.DUCK[e.keyCode]) {
        e.preventDefault();
        if (this.tRex.jumping) {
          // Speed drop, activated only when jump key is not pressed.
          this.tRex.setSpeedDrop();
        } else if (!this.tRex.jumping && !this.tRex.ducking) {
          // Duck.
          this.tRex.setDuck(true);
        }
      }
    } else if (this.crashed && e.type == Runner.events.TOUCHSTART &&
        e.currentTarget == this.containerEl) {
      this.restart();
    }
  },


  /**
   * Process key up.
   * @param {Event} e
   */
  onKeyUp: function(e) {
    var keyCode = String(e.keyCode);
    var isjumpKey = Runner.keycodes.JUMP[keyCode] ||
       e.type == Runner.events.TOUCHEND ||
       e.type == Runner.events.MOUSEDOWN;

    if (this.isRunning() && isjumpKey) {
      this.tRex.endJump();
    } else if (Runner.keycodes.DUCK[keyCode]) {
      this.tRex.speedDrop = false;
      this.tRex.setDuck(false);
    } else if (this.crashed) {
      // Check that enough time has elapsed before allowing jump key to restart.
      var deltaTime = getTimeStamp() - this.time;

      if (Runner.keycodes.RESTART[keyCode] || this.isLeftClickOnCanvas(e) ||
          (deltaTime >= this.config.GAMEOVER_CLEAR_TIME &&
          Runner.keycodes.JUMP[keyCode])) {
        this.restart();
      }
    } else if (this.paused && isjumpKey) {
      // Reset the jump state
      this.tRex.reset();
      this.play();
    }
  },

  /**
   * Returns whether the event was a left click on canvas.
   * On Windows right click is registered as a click.
   * @param {Event} e
   * @return {boolean}
   */
  isLeftClickOnCanvas: function(e) {
    return e.button != null && e.button < 2 &&
        e.type == Runner.events.MOUSEUP && e.target == this.canvas;
  },

  /**
   * RequestAnimationFrame wrapper.
   */
  scheduleNextUpdate: function() {
    if (!this.updatePending) {
      this.updatePending = true;
      this.raqId = requestAnimationFrame(this.update.bind(this));
    }
  },

  /**
   * Whether the game is running.
   * @return {boolean}
   */
  isRunning: function() {
    return !!this.raqId;
  },

  /**
   * Game over state.
   */
  gameOver: function() {
    this.playSound(this.soundFx.HIT);
    vibrate(200);

    this.stop();
    this.crashed = true;
    this.distanceMeter.acheivement = false;

    this.tRex.update(100, Trex.status.CRASHED);

    // Game over panel.
    if (!this.gameOverPanel) {
      this.gameOverPanel = new GameOverPanel(this.canvas,
          this.spriteDef.TEXT_SPRITE, this.spriteDef.RESTART,
          this.dimensions);
    } else {
      this.gameOverPanel.draw();
    }

    // Update the high score.
    if (this.distanceRan > this.highestScore) {
      this.highestScore = Math.ceil(this.distanceRan);
      this.distanceMeter.setHighScore(this.highestScore);
    }

    // Reset the time clock.
    this.time = getTimeStamp();
  },

  stop: function() {
    this.playing = false;
    this.paused = true;
    cancelAnimationFrame(this.raqId);
    this.raqId = 0;
  },

  play: function() {
    if (!this.crashed) {
      this.playing = true;
      this.paused = false;
      this.tRex.update(0, Trex.status.RUNNING);
      this.time = getTimeStamp();
      this.update();
    }
  },

  restart: function() {
    if (!this.raqId) {
      this.playCount++;
      this.runningTime = 0;
      this.playing = true;
      this.paused = false;
      this.crashed = false;
      this.distanceRan = 0;
      this.setSpeed(this.config.SPEED);
      this.time = getTimeStamp();
      this.containerEl.classList.remove(Runner.classes.CRASHED);
      this.clearCanvas();
      this.distanceMeter.reset(this.highestScore);
      this.horizon.reset();
      this.tRex.reset();
      this.playSound(this.soundFx.BUTTON_PRESS);
      this.invert(true);
      this.update();
    }
  },

  /**
   * Pause the game if the tab is not in focus.
   */
  onVisibilityChange: function(e) {
    if (document.hidden || document.webkitHidden || e.type == 'blur' ||
      document.visibilityState != 'visible') {
      this.stop();
    } else if (!this.crashed) {
      this.tRex.reset();
      this.play();
    }
  },

  /**
   * Play a sound.
   * @param {SoundBuffer} soundBuffer
   */
  playSound: function(soundBuffer) {
    if (soundBuffer) {
      var sourceNode = this.audioContext.createBufferSource();
      sourceNode.buffer = soundBuffer;
      sourceNode.connect(this.audioContext.destination);
      sourceNode.start(0);
    }
  },

  /**
   * Inverts the current page / canvas colors.
   * @param {boolean} Whether to reset colors.
   */
  invert: function(reset) {
    if (reset) {
      document.body.classList.toggle(Runner.classes.INVERTED, false);
      this.invertTimer = 0;
      this.inverted = false;
    } else {
      this.inverted = document.body.classList.toggle(Runner.classes.INVERTED,
          this.invertTrigger);
    }
  }
};


/**
 * Updates the canvas size taking into
 * account the backing store pixel ratio and
 * the device pixel ratio.
 *
 * See article by Paul Lewis:
 * http://www.html5rocks.com/en/tutorials/canvas/hidpi/
 *
 * @param {HTMLCanvasElement} canvas
 * @param {number} opt_width
 * @param {number} opt_height
 * @return {boolean} Whether the canvas was scaled.
 */
Runner.updateCanvasScaling = function(canvas, opt_width, opt_height) {
  var context = canvas.getContext('2d');

  // Query the various pixel ratios
  var devicePixelRatio = Math.floor(window.devicePixelRatio) || 1;
  var backingStoreRatio = Math.floor(context.webkitBackingStorePixelRatio) || 1;
  var ratio = devicePixelRatio / backingStoreRatio;

  // Upscale the canvas if the two ratios don't match
  if (devicePixelRatio !== backingStoreRatio) {
    var oldWidth = opt_width || canvas.width;
    var oldHeight = opt_height || canvas.height;

    canvas.width = oldWidth * ratio;
    canvas.height = oldHeight * ratio;

    canvas.style.width = oldWidth + 'px';
    canvas.style.height = oldHeight + 'px';

    // Scale the context to counter the fact that we've manually scaled
    // our canvas element.
    context.scale(ratio, ratio);
    return true;
  } else if (devicePixelRatio == 1) {
    // Reset the canvas width / height. Fixes scaling bug when the page is
    // zoomed and the devicePixelRatio changes accordingly.
    canvas.style.width = canvas.width + 'px';
    canvas.style.height = canvas.height + 'px';
  }
  return false;
};


/**
 * Get random number.
 * @param {number} min
 * @param {number} max
 * @param {number}
 */
function getRandomNum(min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
}


/**
 * Vibrate on mobile devices.
 * @param {number} duration Duration of the vibration in milliseconds.
 */
function vibrate(duration) {
  if (IS_MOBILE && window.navigator.vibrate) {
    window.navigator.vibrate(duration);
  }
}


/**
 * Create canvas element.
 * @param {HTMLElement} container Element to append canvas to.
 * @param {number} width
 * @param {number} height
 * @param {string} opt_classname
 * @return {HTMLCanvasElement}
 */
function createCanvas(container, width, height, opt_classname) {
  var canvas = document.createElement('canvas');
  canvas.className = opt_classname ? Runner.classes.CANVAS + ' ' +
      opt_classname : Runner.classes.CANVAS;
  canvas.width = width;
  canvas.height = height;
  container.appendChild(canvas);

  return canvas;
}


/**
 * Decodes the base 64 audio to ArrayBuffer used by Web Audio.
 * @param {string} base64String
 */
function decodeBase64ToArrayBuffer(base64String) {
  var len = (base64String.length / 4) * 3;
  var str = atob(base64String);
  var arrayBuffer = new ArrayBuffer(len);
  var bytes = new Uint8Array(arrayBuffer);

  for (var i = 0; i < len; i++) {
    bytes[i] = str.charCodeAt(i);
  }
  return bytes.buffer;
}


/**
 * Return the current timestamp.
 * @return {number}
 */
function getTimeStamp() {
  return IS_IOS ? new Date().getTime() : performance.now();
}


//******************************************************************************


/**
 * Game over panel.
 * @param {!HTMLCanvasElement} canvas
 * @param {Object} textImgPos
 * @param {Object} restartImgPos
 * @param {!Object} dimensions Canvas dimensions.
 * @constructor
 */
function GameOverPanel(canvas, textImgPos, restartImgPos, dimensions) {
  this.canvas = canvas;
  this.canvasCtx = canvas.getContext('2d');
  this.canvasDimensions = dimensions;
  this.textImgPos = textImgPos;
  this.restartImgPos = restartImgPos;
  this.draw();
};


/**
 * Dimensions used in the panel.
 * @enum {number}
 */
GameOverPanel.dimensions = {
  TEXT_X: 0,
  TEXT_Y: 13,
  TEXT_WIDTH: 191,
  TEXT_HEIGHT: 11,
  RESTART_WIDTH: 36,
  RESTART_HEIGHT: 32
};


GameOverPanel.prototype = {
  /**
   * Update the panel dimensions.
   * @param {number} width New canvas width.
   * @param {number} opt_height Optional new canvas height.
   */
  updateDimensions: function(width, opt_height) {
    this.canvasDimensions.WIDTH = width;
    if (opt_height) {
      this.canvasDimensions.HEIGHT = opt_height;
    }
  },

  /**
   * Draw the panel.
   */
  draw: function() {
    var dimensions = GameOverPanel.dimensions;

    var centerX = this.canvasDimensions.WIDTH / 2;

    // Game over text.
    var textSourceX = dimensions.TEXT_X;
    var textSourceY = dimensions.TEXT_Y;
    var textSourceWidth = dimensions.TEXT_WIDTH;
    var textSourceHeight = dimensions.TEXT_HEIGHT;

    var textTargetX = Math.round(centerX - (dimensions.TEXT_WIDTH / 2));
    var textTargetY = Math.round((this.canvasDimensions.HEIGHT - 25) / 3);
    var textTargetWidth = dimensions.TEXT_WIDTH;
    var textTargetHeight = dimensions.TEXT_HEIGHT;

    var restartSourceWidth = dimensions.RESTART_WIDTH;
    var restartSourceHeight = dimensions.RESTART_HEIGHT;
    var restartTargetX = centerX - (dimensions.RESTART_WIDTH / 2);
    var restartTargetY = this.canvasDimensions.HEIGHT / 2;

    if (IS_HIDPI) {
      textSourceY *= 2;
      textSourceX *= 2;
      textSourceWidth *= 2;
      textSourceHeight *= 2;
      restartSourceWidth *= 2;
      restartSourceHeight *= 2;
    }

    textSourceX += this.textImgPos.x;
    textSourceY += this.textImgPos.y;

    // Game over text from sprite.
    this.canvasCtx.drawImage(Runner.imageSprite,
        textSourceX, textSourceY, textSourceWidth, textSourceHeight,
        textTargetX, textTargetY, textTargetWidth, textTargetHeight);

    // Restart button.
    this.canvasCtx.drawImage(Runner.imageSprite,
        this.restartImgPos.x, this.restartImgPos.y,
        restartSourceWidth, restartSourceHeight,
        restartTargetX, restartTargetY, dimensions.RESTART_WIDTH,
        dimensions.RESTART_HEIGHT);
  }
};


//******************************************************************************

/**
 * Check for a collision.
 * @param {!Obstacle} obstacle
 * @param {!Trex} tRex T-rex object.
 * @param {HTMLCanvasContext} opt_canvasCtx Optional canvas context for drawing
 *    collision boxes.
 * @return {Array<CollisionBox>}
 */
function checkForCollision(obstacle, tRex, opt_canvasCtx) {
  var obstacleBoxXPos = Runner.defaultDimensions.WIDTH + obstacle.xPos;

  // Adjustments are made to the bounding box as there is a 1 pixel white
  // border around the t-rex and obstacles.
  var tRexBox = new CollisionBox(
      tRex.xPos + 1,
      tRex.yPos + 1,
      tRex.config.WIDTH - 2,
      tRex.config.HEIGHT - 2);

  var obstacleBox = new CollisionBox(
      obstacle.xPos + 1,
      obstacle.yPos + 1,
      obstacle.typeConfig.width * obstacle.size - 2,
      obstacle.typeConfig.height - 2);

  // Debug outer box
  if (opt_canvasCtx) {
    drawCollisionBoxes(opt_canvasCtx, tRexBox, obstacleBox);
  }

  // Simple outer bounds check.
  if (boxCompare(tRexBox, obstacleBox)) {
    var collisionBoxes = obstacle.collisionBoxes;
    var tRexCollisionBoxes = tRex.ducking ?
        Trex.collisionBoxes.DUCKING : Trex.collisionBoxes.RUNNING;

    // Detailed axis aligned box check.
    for (var t = 0; t < tRexCollisionBoxes.length; t++) {
      for (var i = 0; i < collisionBoxes.length; i++) {
        // Adjust the box to actual positions.
        var adjTrexBox =
            createAdjustedCollisionBox(tRexCollisionBoxes[t], tRexBox);
        var adjObstacleBox =
            createAdjustedCollisionBox(collisionBoxes[i], obstacleBox);
        var crashed = boxCompare(adjTrexBox, adjObstacleBox);

        // Draw boxes for debug.
        if (opt_canvasCtx) {
          drawCollisionBoxes(opt_canvasCtx, adjTrexBox, adjObstacleBox);
        }

        if (crashed) {
          return [adjTrexBox, adjObstacleBox];
        }
      }
    }
  }
  return false;
};


/**
 * Adjust the collision box.
 * @param {!CollisionBox} box The original box.
 * @param {!CollisionBox} adjustment Adjustment box.
 * @return {CollisionBox} The adjusted collision box object.
 */
function createAdjustedCollisionBox(box, adjustment) {
  return new CollisionBox(
      box.x + adjustment.x,
      box.y + adjustment.y,
      box.width,
      box.height);
};


/**
 * Draw the collision boxes for debug.
 */
function drawCollisionBoxes(canvasCtx, tRexBox, obstacleBox) {
  canvasCtx.save();
  canvasCtx.strokeStyle = '#f00';
  canvasCtx.strokeRect(tRexBox.x, tRexBox.y, tRexBox.width, tRexBox.height);

  canvasCtx.strokeStyle = '#0f0';
  canvasCtx.strokeRect(obstacleBox.x, obstacleBox.y,
      obstacleBox.width, obstacleBox.height);
  canvasCtx.restore();
};


/**
 * Compare two collision boxes for a collision.
 * @param {CollisionBox} tRexBox
 * @param {CollisionBox} obstacleBox
 * @return {boolean} Whether the boxes intersected.
 */
function boxCompare(tRexBox, obstacleBox) {
  var crashed = false;
  var tRexBoxX = tRexBox.x;
  var tRexBoxY = tRexBox.y;

  var obstacleBoxX = obstacleBox.x;
  var obstacleBoxY = obstacleBox.y;

  // Axis-Aligned Bounding Box method.
  if (tRexBox.x < obstacleBoxX + obstacleBox.width &&
      tRexBox.x + tRexBox.width > obstacleBoxX &&
      tRexBox.y < obstacleBox.y + obstacleBox.height &&
      tRexBox.height + tRexBox.y > obstacleBox.y) {
    crashed = true;
  }

  return crashed;
};


//******************************************************************************

/**
 * Collision box object.
 * @param {number} x X position.
 * @param {number} y Y Position.
 * @param {number} w Width.
 * @param {number} h Height.
 */
function CollisionBox(x, y, w, h) {
  this.x = x;
  this.y = y;
  this.width = w;
  this.height = h;
};


//******************************************************************************

/**
 * Obstacle.
 * @param {HTMLCanvasCtx} canvasCtx
 * @param {Obstacle.type} type
 * @param {Object} spritePos Obstacle position in sprite.
 * @param {Object} dimensions
 * @param {number} gapCoefficient Mutipler in determining the gap.
 * @param {number} speed
 * @param {number} opt_xOffset
 */
function Obstacle(canvasCtx, type, spriteImgPos, dimensions,
    gapCoefficient, speed, opt_xOffset) {

  this.canvasCtx = canvasCtx;
  this.spritePos = spriteImgPos;
  this.typeConfig = type;
  this.gapCoefficient = gapCoefficient;
  this.size = getRandomNum(1, Obstacle.MAX_OBSTACLE_LENGTH);
  this.dimensions = dimensions;
  this.remove = false;
  this.xPos = dimensions.WIDTH + (opt_xOffset || 0);
  this.yPos = 0;
  this.width = 0;
  this.collisionBoxes = [];
  this.gap = 0;
  this.speedOffset = 0;

  // For animated obstacles.
  this.currentFrame = 0;
  this.timer = 0;

  this.init(speed);
};

/**
 * Coefficient for calculating the maximum gap.
 * @const
 */
Obstacle.MAX_GAP_COEFFICIENT = 1.5;

/**
 * Maximum obstacle grouping count.
 * @const
 */
Obstacle.MAX_OBSTACLE_LENGTH = 3,


Obstacle.prototype = {
  /**
   * Initialise the DOM for the obstacle.
   * @param {number} speed
   */
  init: function(speed) {
    this.cloneCollisionBoxes();

    // Only allow sizing if we're at the right speed.
    if (this.size > 1 && this.typeConfig.multipleSpeed > speed) {
      this.size = 1;
    }

    this.width = this.typeConfig.width * this.size;

    // Check if obstacle can be positioned at various heights.
    if (Array.isArray(this.typeConfig.yPos))  {
      var yPosConfig = IS_MOBILE ? this.typeConfig.yPosMobile :
          this.typeConfig.yPos;
      this.yPos = yPosConfig[getRandomNum(0, yPosConfig.length - 1)];
    } else {
      this.yPos = this.typeConfig.yPos;
    }

    this.draw();

    // Make collision box adjustments,
    // Central box is adjusted to the size as one box.
    //      ____        ______        ________
    //    _|   |-|    _|     |-|    _|       |-|
    //   | |<->| |   | |<--->| |   | |<----->| |
    //   | | 1 | |   | |  2  | |   | |   3   | |
    //   |_|___|_|   |_|_____|_|   |_|_______|_|
    //
    if (this.size > 1) {
      this.collisionBoxes[1].width = this.width - this.collisionBoxes[0].width -
          this.collisionBoxes[2].width;
      this.collisionBoxes[2].x = this.width - this.collisionBoxes[2].width;
    }

    // For obstacles that go at a different speed from the horizon.
    if (this.typeConfig.speedOffset) {
      this.speedOffset = Math.random() > 0.5 ? this.typeConfig.speedOffset :
          -this.typeConfig.speedOffset;
    }

    this.gap = this.getGap(this.gapCoefficient, speed);
  },

  /**
   * Draw and crop based on size.
   */
  draw: function() {
    var sourceWidth = this.typeConfig.width;
    var sourceHeight = this.typeConfig.height;

    if (IS_HIDPI) {
      sourceWidth = sourceWidth * 2;
      sourceHeight = sourceHeight * 2;
    }

    // X position in sprite.
    var sourceX = (sourceWidth * this.size) * (0.5 * (this.size - 1)) +
        this.spritePos.x;

    // Animation frames.
    if (this.currentFrame > 0) {
      sourceX += sourceWidth * this.currentFrame;
    }

    this.canvasCtx.drawImage(Runner.imageSprite,
      sourceX, this.spritePos.y,
      sourceWidth * this.size, sourceHeight,
      this.xPos, this.yPos,
      this.typeConfig.width * this.size, this.typeConfig.height);
  },

  /**
   * Obstacle frame update.
   * @param {number} deltaTime
   * @param {number} speed
   */
  update: function(deltaTime, speed) {
    if (!this.remove) {
      if (this.typeConfig.speedOffset) {
        speed += this.speedOffset;
      }
      this.xPos -= Math.floor((speed * FPS / 1000) * deltaTime);

      // Update frame
      if (this.typeConfig.numFrames) {
        this.timer += deltaTime;
        if (this.timer >= this.typeConfig.frameRate) {
          this.currentFrame =
              this.currentFrame == this.typeConfig.numFrames - 1 ?
              0 : this.currentFrame + 1;
          this.timer = 0;
        }
      }
      this.draw();

      if (!this.isVisible()) {
        this.remove = true;
      }
    }
  },

  /**
   * Calculate a random gap size.
   * - Minimum gap gets wider as speed increses
   * @param {number} gapCoefficient
   * @param {number} speed
   * @return {number} The gap size.
   */
  getGap: function(gapCoefficient, speed) {
    var minGap = Math.round(this.width * speed +
          this.typeConfig.minGap * gapCoefficient);
    var maxGap = Math.round(minGap * Obstacle.MAX_GAP_COEFFICIENT);
    return getRandomNum(minGap, maxGap);
  },

  /**
   * Check if obstacle is visible.
   * @return {boolean} Whether the obstacle is in the game area.
   */
  isVisible: function() {
    return this.xPos + this.width > 0;
  },

  /**
   * Make a copy of the collision boxes, since these will change based on
   * obstacle type and size.
   */
  cloneCollisionBoxes: function() {
    var collisionBoxes = this.typeConfig.collisionBoxes;

    for (var i = collisionBoxes.length - 1; i >= 0; i--) {
      this.collisionBoxes[i] = new CollisionBox(collisionBoxes[i].x,
          collisionBoxes[i].y, collisionBoxes[i].width,
          collisionBoxes[i].height);
    }
  }
};


/**
 * Obstacle definitions.
 * minGap: minimum pixel space betweeen obstacles.
 * multipleSpeed: Speed at which multiples are allowed.
 * speedOffset: speed faster / slower than the horizon.
 * minSpeed: Minimum speed which the obstacle can make an appearance.
 */
Obstacle.types = [
  {
    type: 'CACTUS_SMALL',
    width: 17,
    height: 35,
    yPos: 105,
    multipleSpeed: 4,
    minGap: 120,
    minSpeed: 0,
    collisionBoxes: [
      new CollisionBox(0, 7, 5, 27),
      new CollisionBox(4, 0, 6, 34),
      new CollisionBox(10, 4, 7, 14)
    ]
  },
  {
    type: 'CACTUS_LARGE',
    width: 25,
    height: 50,
    yPos: 90,
    multipleSpeed: 7,
    minGap: 120,
    minSpeed: 0,
    collisionBoxes: [
      new CollisionBox(0, 12, 7, 38),
      new CollisionBox(8, 0, 7, 49),
      new CollisionBox(13, 10, 10, 38)
    ]
  },
  {
    type: 'PTERODACTYL',
    width: 46,
    height: 40,
    yPos: [ 100, 75, 50 ], // Variable height.
    yPosMobile: [ 100, 50 ], // Variable height mobile.
    multipleSpeed: 999,
    minSpeed: 8.5,
    minGap: 150,
    collisionBoxes: [
      new CollisionBox(15, 15, 16, 5),
      new CollisionBox(18, 21, 24, 6),
      new CollisionBox(2, 14, 4, 3),
      new CollisionBox(6, 10, 4, 7),
      new CollisionBox(10, 8, 6, 9)
    ],
    numFrames: 2,
    frameRate: 1000/6,
    speedOffset: .8
  }
];


//******************************************************************************
/**
 * T-rex game character.
 * @param {HTMLCanvas} canvas
 * @param {Object} spritePos Positioning within image sprite.
 * @constructor
 */
function Trex(canvas, spritePos) {
  this.canvas = canvas;
  this.canvasCtx = canvas.getContext('2d');
  this.spritePos = spritePos;
  this.xPos = 0;
  this.yPos = 0;
  // Position when on the ground.
  this.groundYPos = 0;
  this.currentFrame = 0;
  this.currentAnimFrames = [];
  this.blinkDelay = 0;
  this.blinkCount = 0;
  this.animStartTime = 0;
  this.timer = 0;
  this.msPerFrame = 1000 / FPS;
  this.config = Trex.config;
  // Current status.
  this.status = Trex.status.WAITING;

  this.jumping = false;
  this.ducking = false;
  this.jumpVelocity = 0;
  this.reachedMinHeight = false;
  this.speedDrop = false;
  this.jumpCount = 0;
  this.jumpspotX = 0;

  this.init();
};


/**
 * T-rex player config.
 * @enum {number}
 */
Trex.config = {
  DROP_VELOCITY: -5,
  GRAVITY: 0.6,
  HEIGHT: 47,
  HEIGHT_DUCK: 25,
  INIITAL_JUMP_VELOCITY: -10,
  INTRO_DURATION: 1500,
  MAX_JUMP_HEIGHT: 30,
  MIN_JUMP_HEIGHT: 30,
  SPEED_DROP_COEFFICIENT: 3,
  SPRITE_WIDTH: 262,
  START_X_POS: 50,
  WIDTH: 44,
  WIDTH_DUCK: 59
};


/**
 * Used in collision detection.
 * @type {Array<CollisionBox>}
 */
Trex.collisionBoxes = {
  DUCKING: [
    new CollisionBox(1, 18, 55, 25)
  ],
  RUNNING: [
    new CollisionBox(22, 0, 17, 16),
    new CollisionBox(1, 18, 30, 9),
    new CollisionBox(10, 35, 14, 8),
    new CollisionBox(1, 24, 29, 5),
    new CollisionBox(5, 30, 21, 4),
    new CollisionBox(9, 34, 15, 4)
  ]
};


/**
 * Animation states.
 * @enum {string}
 */
Trex.status = {
  CRASHED: 'CRASHED',
  DUCKING: 'DUCKING',
  JUMPING: 'JUMPING',
  RUNNING: 'RUNNING',
  WAITING: 'WAITING'
};

/**
 * Blinking coefficient.
 * @const
 */
Trex.BLINK_TIMING = 7000;


/**
 * Animation config for different states.
 * @enum {Object}
 */
Trex.animFrames = {
  WAITING: {
    frames: [44, 0],
    msPerFrame: 1000 / 3
  },
  RUNNING: {
    frames: [88, 132],
    msPerFrame: 1000 / 12
  },
  CRASHED: {
    frames: [220],
    msPerFrame: 1000 / 60
  },
  JUMPING: {
    frames: [0],
    msPerFrame: 1000 / 60
  },
  DUCKING: {
    frames: [262, 321],
    msPerFrame: 1000 / 8
  }
};


Trex.prototype = {
  /**
   * T-rex player initaliser.
   * Sets the t-rex to blink at random intervals.
   */
  init: function() {
    this.groundYPos = Runner.defaultDimensions.HEIGHT - this.config.HEIGHT -
        Runner.config.BOTTOM_PAD;
    this.yPos = this.groundYPos;
    this.minJumpHeight = this.groundYPos - this.config.MIN_JUMP_HEIGHT;

    this.draw(0, 0);
    this.update(0, Trex.status.WAITING);
  },

  /**
   * Setter for the jump velocity.
   * The approriate drop velocity is also set.
   */
  setJumpVelocity: function(setting) {
    this.config.INIITAL_JUMP_VELOCITY = -setting;
    this.config.DROP_VELOCITY = -setting / 2;
  },

  /**
   * Set the animation status.
   * @param {!number} deltaTime
   * @param {Trex.status} status Optional status to switch to.
   */
  update: function(deltaTime, opt_status) {
    this.timer += deltaTime;

    // Update the status.
    if (opt_status) {
      this.status = opt_status;
      this.currentFrame = 0;
      this.msPerFrame = Trex.animFrames[opt_status].msPerFrame;
      this.currentAnimFrames = Trex.animFrames[opt_status].frames;

      if (opt_status == Trex.status.WAITING) {
        this.animStartTime = getTimeStamp();
        this.setBlinkDelay();
      }
    }

    // Game intro animation, T-rex moves in from the left.
    if (this.playingIntro && this.xPos < this.config.START_X_POS) {
      this.xPos += Math.round((this.config.START_X_POS /
          this.config.INTRO_DURATION) * deltaTime);
    }

    if (this.status == Trex.status.WAITING) {
      this.blink(getTimeStamp());
    } else {
      this.draw(this.currentAnimFrames[this.currentFrame], 0);
    }

    // Update the frame position.
    if (this.timer >= this.msPerFrame) {
      this.currentFrame = this.currentFrame ==
          this.currentAnimFrames.length - 1 ? 0 : this.currentFrame + 1;
      this.timer = 0;
    }

    // Speed drop becomes duck if the down key is still being pressed.
    if (this.speedDrop && this.yPos == this.groundYPos) {
      this.speedDrop = false;
      this.setDuck(true);
    }
  },

  /**
   * Draw the t-rex to a particular position.
   * @param {number} x
   * @param {number} y
   */
  draw: function(x, y) {
    var sourceX = x;
    var sourceY = y;
    var sourceWidth = this.ducking && this.status != Trex.status.CRASHED ?
        this.config.WIDTH_DUCK : this.config.WIDTH;
    var sourceHeight = this.config.HEIGHT;

    if (IS_HIDPI) {
      sourceX *= 2;
      sourceY *= 2;
      sourceWidth *= 2;
      sourceHeight *= 2;
    }

    // Adjustments for sprite sheet position.
    sourceX += this.spritePos.x;
    sourceY += this.spritePos.y;

    // Ducking.
    if (this.ducking && this.status != Trex.status.CRASHED) {
      this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
          sourceWidth, sourceHeight,
          this.xPos, this.yPos,
          this.config.WIDTH_DUCK, this.config.HEIGHT);
    } else {
      // Crashed whilst ducking. Trex is standing up so needs adjustment.
      if (this.ducking && this.status == Trex.status.CRASHED) {
        this.xPos++;
      }
      // Standing / running
      this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
          sourceWidth, sourceHeight,
          this.xPos, this.yPos,
          this.config.WIDTH, this.config.HEIGHT);
    }
  },

  /**
   * Sets a random time for the blink to happen.
   */
  setBlinkDelay: function() {
    this.blinkDelay = Math.ceil(Math.random() * Trex.BLINK_TIMING);
  },

  /**
   * Make t-rex blink at random intervals.
   * @param {number} time Current time in milliseconds.
   */
  blink: function(time) {
    var deltaTime = time - this.animStartTime;

    if (deltaTime >= this.blinkDelay) {
      this.draw(this.currentAnimFrames[this.currentFrame], 0);

      if (this.currentFrame == 1) {
        // Set new random delay to blink.
        this.setBlinkDelay();
        this.animStartTime = time;
        this.blinkCount++;
      }
    }
  },

  /**
   * Initialise a jump.
   * @param {number} speed
   */
  startJump: function(speed) {
    if (!this.jumping) {
      this.update(0, Trex.status.JUMPING);
      // Tweak the jump velocity based on the speed.
      this.jumpVelocity = this.config.INIITAL_JUMP_VELOCITY - (speed / 10);
      this.jumping = true;
      this.reachedMinHeight = false;
      this.speedDrop = false;
    }
  },

  /**
   * Jump is complete, falling down.
   */
  endJump: function() {
    if (this.reachedMinHeight &&
        this.jumpVelocity < this.config.DROP_VELOCITY) {
      this.jumpVelocity = this.config.DROP_VELOCITY;
    }
  },

  /**
   * Update frame for a jump.
   * @param {number} deltaTime
   * @param {number} speed
   */
  updateJump: function(deltaTime, speed) {
    var msPerFrame = Trex.animFrames[this.status].msPerFrame;
    var framesElapsed = deltaTime / msPerFrame;

    // Speed drop makes Trex fall faster.
    if (this.speedDrop) {
      this.yPos += Math.round(this.jumpVelocity *
          this.config.SPEED_DROP_COEFFICIENT * framesElapsed);
    } else {
      this.yPos += Math.round(this.jumpVelocity * framesElapsed);
    }

    this.jumpVelocity += this.config.GRAVITY * framesElapsed;

    // Minimum height has been reached.
    if (this.yPos < this.minJumpHeight || this.speedDrop) {
      this.reachedMinHeight = true;
    }

    // Reached max height
    if (this.yPos < this.config.MAX_JUMP_HEIGHT || this.speedDrop) {
      this.endJump();
    }

    // Back down at ground level. Jump completed.
    if (this.yPos > this.groundYPos) {
      this.reset();
      this.jumpCount++;
    }

    this.update(deltaTime);
  },

  /**
   * Set the speed drop. Immediately cancels the current jump.
   */
  setSpeedDrop: function() {
    this.speedDrop = true;
    this.jumpVelocity = 1;
  },

  /**
   * @param {boolean} isDucking.
   */
  setDuck: function(isDucking) {
    if (isDucking && this.status != Trex.status.DUCKING) {
      this.update(0, Trex.status.DUCKING);
      this.ducking = true;
    } else if (this.status == Trex.status.DUCKING) {
      this.update(0, Trex.status.RUNNING);
      this.ducking = false;
    }
  },

  /**
   * Reset the t-rex to running at start of game.
   */
  reset: function() {
    this.yPos = this.groundYPos;
    this.jumpVelocity = 0;
    this.jumping = false;
    this.ducking = false;
    this.update(0, Trex.status.RUNNING);
    this.midair = false;
    this.speedDrop = false;
    this.jumpCount = 0;
  }
};


//******************************************************************************

/**
 * Handles displaying the distance meter.
 * @param {!HTMLCanvasElement} canvas
 * @param {Object} spritePos Image position in sprite.
 * @param {number} canvasWidth
 * @constructor
 */
function DistanceMeter(canvas, spritePos, canvasWidth) {
  this.canvas = canvas;
  this.canvasCtx = canvas.getContext('2d');
  this.image = Runner.imageSprite;
  this.spritePos = spritePos;
  this.x = 0;
  this.y = 5;

  this.currentDistance = 0;
  this.maxScore = 0;
  this.highScore = 0;
  this.container = null;

  this.digits = [];
  this.acheivement = false;
  this.defaultString = '';
  this.flashTimer = 0;
  this.flashIterations = 0;
  this.invertTrigger = false;

  this.config = DistanceMeter.config;
  this.maxScoreUnits = this.config.MAX_DISTANCE_UNITS;
  this.init(canvasWidth);
};


/**
 * @enum {number}
 */
DistanceMeter.dimensions = {
  WIDTH: 10,
  HEIGHT: 13,
  DEST_WIDTH: 11
};


/**
 * Y positioning of the digits in the sprite sheet.
 * X position is always 0.
 * @type {Array<number>}
 */
DistanceMeter.yPos = [0, 13, 27, 40, 53, 67, 80, 93, 107, 120];


/**
 * Distance meter config.
 * @enum {number}
 */
DistanceMeter.config = {
  // Number of digits.
  MAX_DISTANCE_UNITS: 5,

  // Distance that causes achievement animation.
  ACHIEVEMENT_DISTANCE: 100,

  // Used for conversion from pixel distance to a scaled unit.
  COEFFICIENT: 0.025,

  // Flash duration in milliseconds.
  FLASH_DURATION: 1000 / 4,

  // Flash iterations for achievement animation.
  FLASH_ITERATIONS: 3
};


DistanceMeter.prototype = {
  /**
   * Initialise the distance meter to '00000'.
   * @param {number} width Canvas width in px.
   */
  init: function(width) {
    var maxDistanceStr = '';

    this.calcXPos(width);
    this.maxScore = this.maxScoreUnits;
    for (var i = 0; i < this.maxScoreUnits; i++) {
      this.draw(i, 0);
      this.defaultString += '0';
      maxDistanceStr += '9';
    }

    this.maxScore = parseInt(maxDistanceStr);
  },

  /**
   * Calculate the xPos in the canvas.
   * @param {number} canvasWidth
   */
  calcXPos: function(canvasWidth) {
    this.x = canvasWidth - (DistanceMeter.dimensions.DEST_WIDTH *
        (this.maxScoreUnits + 1));
  },

  /**
   * Draw a digit to canvas.
   * @param {number} digitPos Position of the digit.
   * @param {number} value Digit value 0-9.
   * @param {boolean} opt_highScore Whether drawing the high score.
   */
  draw: function(digitPos, value, opt_highScore) {
    var sourceWidth = DistanceMeter.dimensions.WIDTH;
    var sourceHeight = DistanceMeter.dimensions.HEIGHT;
    var sourceX = DistanceMeter.dimensions.WIDTH * value;
    var sourceY = 0;

    var targetX = digitPos * DistanceMeter.dimensions.DEST_WIDTH;
    var targetY = this.y;
    var targetWidth = DistanceMeter.dimensions.WIDTH;
    var targetHeight = DistanceMeter.dimensions.HEIGHT;

    // For high DPI we 2x source values.
    if (IS_HIDPI) {
      sourceWidth *= 2;
      sourceHeight *= 2;
      sourceX *= 2;
    }

    sourceX += this.spritePos.x;
    sourceY += this.spritePos.y;

    this.canvasCtx.save();

    if (opt_highScore) {
      // Left of the current score.
      var highScoreX = this.x - (this.maxScoreUnits * 2) *
          DistanceMeter.dimensions.WIDTH;
      this.canvasCtx.translate(highScoreX, this.y);
    } else {
      this.canvasCtx.translate(this.x, this.y);
    }

    this.canvasCtx.drawImage(this.image, sourceX, sourceY,
        sourceWidth, sourceHeight,
        targetX, targetY,
        targetWidth, targetHeight
      );

    this.canvasCtx.restore();
  },

  /**
   * Covert pixel distance to a 'real' distance.
   * @param {number} distance Pixel distance ran.
   * @return {number} The 'real' distance ran.
   */
  getActualDistance: function(distance) {
    return distance ? Math.round(distance * this.config.COEFFICIENT) : 0;
  },

  /**
   * Update the distance meter.
   * @param {number} distance
   * @param {number} deltaTime
   * @return {boolean} Whether the acheivement sound fx should be played.
   */
  update: function(deltaTime, distance) {
    var paint = true;
    var playSound = false;

    if (!this.acheivement) {
      distance = this.getActualDistance(distance);
      // Score has gone beyond the initial digit count.
      if (distance > this.maxScore && this.maxScoreUnits ==
        this.config.MAX_DISTANCE_UNITS) {
        this.maxScoreUnits++;
        this.maxScore = parseInt(this.maxScore + '9');
      } else {
        this.distance = 0;
      }

      if (distance > 0) {
        // Acheivement unlocked
        if (distance % this.config.ACHIEVEMENT_DISTANCE == 0) {
          // Flash score and play sound.
          this.acheivement = true;
          this.flashTimer = 0;
          playSound = true;
        }

        // Create a string representation of the distance with leading 0.
        var distanceStr = (this.defaultString +
            distance).substr(-this.maxScoreUnits);
        this.digits = distanceStr.split('');
      } else {
        this.digits = this.defaultString.split('');
      }
    } else {
      // Control flashing of the score on reaching acheivement.
      if (this.flashIterations <= this.config.FLASH_ITERATIONS) {
        this.flashTimer += deltaTime;

        if (this.flashTimer < this.config.FLASH_DURATION) {
          paint = false;
        } else if (this.flashTimer >
            this.config.FLASH_DURATION * 2) {
          this.flashTimer = 0;
          this.flashIterations++;
        }
      } else {
        this.acheivement = false;
        this.flashIterations = 0;
        this.flashTimer = 0;
      }
    }

    // Draw the digits if not flashing.
    if (paint) {
      for (var i = this.digits.length - 1; i >= 0; i--) {
        this.draw(i, parseInt(this.digits[i]));
      }
    }

    this.drawHighScore();
    return playSound;
  },

  /**
   * Draw the high score.
   */
  drawHighScore: function() {
    this.canvasCtx.save();
    this.canvasCtx.globalAlpha = .8;
    for (var i = this.highScore.length - 1; i >= 0; i--) {
      this.draw(i, parseInt(this.highScore[i], 10), true);
    }
    this.canvasCtx.restore();
  },

  /**
   * Set the highscore as a array string.
   * Position of char in the sprite: H - 10, I - 11.
   * @param {number} distance Distance ran in pixels.
   */
  setHighScore: function(distance) {
    distance = this.getActualDistance(distance);
    var highScoreStr = (this.defaultString +
        distance).substr(-this.maxScoreUnits);

    this.highScore = ['10', '11', ''].concat(highScoreStr.split(''));
  },

  /**
   * Reset the distance meter back to '00000'.
   */
  reset: function() {
    this.update(0);
    this.acheivement = false;
  }
};


//******************************************************************************

/**
 * Cloud background item.
 * Similar to an obstacle object but without collision boxes.
 * @param {HTMLCanvasElement} canvas Canvas element.
 * @param {Object} spritePos Position of image in sprite.
 * @param {number} containerWidth
 */
function Cloud(canvas, spritePos, containerWidth) {
  this.canvas = canvas;
  this.canvasCtx = this.canvas.getContext('2d');
  this.spritePos = spritePos;
  this.containerWidth = containerWidth;
  this.xPos = containerWidth;
  this.yPos = 0;
  this.remove = false;
  this.cloudGap = getRandomNum(Cloud.config.MIN_CLOUD_GAP,
      Cloud.config.MAX_CLOUD_GAP);

  this.init();
};


/**
 * Cloud object config.
 * @enum {number}
 */
Cloud.config = {
  HEIGHT: 14,
  MAX_CLOUD_GAP: 400,
  MAX_SKY_LEVEL: 30,
  MIN_CLOUD_GAP: 100,
  MIN_SKY_LEVEL: 71,
  WIDTH: 46
};


Cloud.prototype = {
  /**
   * Initialise the cloud. Sets the Cloud height.
   */
  init: function() {
    this.yPos = getRandomNum(Cloud.config.MAX_SKY_LEVEL,
        Cloud.config.MIN_SKY_LEVEL);
    this.draw();
  },

  /**
   * Draw the cloud.
   */
  draw: function() {
    this.canvasCtx.save();
    var sourceWidth = Cloud.config.WIDTH;
    var sourceHeight = Cloud.config.HEIGHT;

    if (IS_HIDPI) {
      sourceWidth = sourceWidth * 2;
      sourceHeight = sourceHeight * 2;
    }

    this.canvasCtx.drawImage(Runner.imageSprite, this.spritePos.x,
        this.spritePos.y,
        sourceWidth, sourceHeight,
        this.xPos, this.yPos,
        Cloud.config.WIDTH, Cloud.config.HEIGHT);

    this.canvasCtx.restore();
  },

  /**
   * Update the cloud position.
   * @param {number} speed
   */
  update: function(speed) {
    if (!this.remove) {
      this.xPos -= Math.ceil(speed);
      this.draw();

      // Mark as removeable if no longer in the canvas.
      if (!this.isVisible()) {
        this.remove = true;
      }
    }
  },

  /**
   * Check if the cloud is visible on the stage.
   * @return {boolean}
   */
  isVisible: function() {
    return this.xPos + Cloud.config.WIDTH > 0;
  }
};


//******************************************************************************

/**
 * Nightmode shows a moon and stars on the horizon.
 */
function NightMode(canvas, spritePos, containerWidth) {
  this.spritePos = spritePos;
  this.canvas = canvas;
  this.canvasCtx = canvas.getContext('2d');
  this.xPos = containerWidth - 50;
  this.yPos = 30;
  this.currentPhase = 0;
  this.opacity = 0;
  this.containerWidth = containerWidth;
  this.stars = [];
  this.drawStars = false;
  this.placeStars();
};

/**
 * @enum {number}
 */
NightMode.config = {
  FADE_SPEED: 0.035,
  HEIGHT: 40,
  MOON_SPEED: 0.25,
  NUM_STARS: 2,
  STAR_SIZE: 9,
  STAR_SPEED: 0.3,
  STAR_MAX_Y: 70,
  WIDTH: 20
};

NightMode.phases = [140, 120, 100, 60, 40, 20, 0];

NightMode.prototype = {
  /**
   * Update moving moon, changing phases.
   * @param {boolean} activated Whether night mode is activated.
   * @param {number} delta
   */
  update: function(activated, delta) {
    // Moon phase.
    if (activated && this.opacity == 0) {
      this.currentPhase++;

      if (this.currentPhase >= NightMode.phases.length) {
        this.currentPhase = 0;
      }
    }

    // Fade in / out.
    if (activated && (this.opacity < 1 || this.opacity == 0)) {
      this.opacity += NightMode.config.FADE_SPEED;
    } else if (this.opacity > 0) {
      this.opacity -= NightMode.config.FADE_SPEED;
    }

    // Set moon positioning.
    if (this.opacity > 0) {
      this.xPos = this.updateXPos(this.xPos, NightMode.config.MOON_SPEED);

      // Update stars.
      if (this.drawStars) {
         for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
            this.stars[i].x = this.updateXPos(this.stars[i].x,
                NightMode.config.STAR_SPEED);
         }
      }
      this.draw();
    } else {
      this.opacity = 0;
      this.placeStars();
    }
    this.drawStars = true;
  },

  updateXPos: function(currentPos, speed) {
    if (currentPos < -NightMode.config.WIDTH) {
      currentPos = this.containerWidth;
    } else {
      currentPos -= speed;
    }
    return currentPos;
  },

  draw: function() {
    var moonSourceWidth = this.currentPhase == 3 ? NightMode.config.WIDTH * 2 :
         NightMode.config.WIDTH;
    var moonSourceHeight = NightMode.config.HEIGHT;
    var moonSourceX = this.spritePos.x + NightMode.phases[this.currentPhase];
    var moonOutputWidth = moonSourceWidth;
    var starSize = NightMode.config.STAR_SIZE;
    var starSourceX = Runner.spriteDefinition.LDPI.STAR.x;

    if (IS_HIDPI) {
      moonSourceWidth *= 2;
      moonSourceHeight *= 2;
      moonSourceX = this.spritePos.x +
          (NightMode.phases[this.currentPhase] * 2);
      starSize *= 2;
      starSourceX = Runner.spriteDefinition.HDPI.STAR.x;
    }

    this.canvasCtx.save();
    this.canvasCtx.globalAlpha = this.opacity;

    // Stars.
    if (this.drawStars) {
      for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
        this.canvasCtx.drawImage(Runner.imageSprite,
            starSourceX, this.stars[i].sourceY, starSize, starSize,
            Math.round(this.stars[i].x), this.stars[i].y,
            NightMode.config.STAR_SIZE, NightMode.config.STAR_SIZE);
      }
    }

    // Moon.
    this.canvasCtx.drawImage(Runner.imageSprite, moonSourceX,
        this.spritePos.y, moonSourceWidth, moonSourceHeight,
        Math.round(this.xPos), this.yPos,
        moonOutputWidth, NightMode.config.HEIGHT);

    this.canvasCtx.globalAlpha = 1;
    this.canvasCtx.restore();
  },

  // Do star placement.
  placeStars: function() {
    var segmentSize = Math.round(this.containerWidth /
        NightMode.config.NUM_STARS);

    for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
      this.stars[i] = {};
      this.stars[i].x = getRandomNum(segmentSize * i, segmentSize * (i + 1));
      this.stars[i].y = getRandomNum(0, NightMode.config.STAR_MAX_Y);

      if (IS_HIDPI) {
        this.stars[i].sourceY = Runner.spriteDefinition.HDPI.STAR.y +
            NightMode.config.STAR_SIZE * 2 * i;
      } else {
        this.stars[i].sourceY = Runner.spriteDefinition.LDPI.STAR.y +
            NightMode.config.STAR_SIZE * i;
      }
    }
  },

  reset: function() {
    this.currentPhase = 0;
    this.opacity = 0;
    this.update(false);
  }

};


//******************************************************************************

/**
 * Horizon Line.
 * Consists of two connecting lines. Randomly assigns a flat / bumpy horizon.
 * @param {HTMLCanvasElement} canvas
 * @param {Object} spritePos Horizon position in sprite.
 * @constructor
 */
function HorizonLine(canvas, spritePos) {
  this.spritePos = spritePos;
  this.canvas = canvas;
  this.canvasCtx = canvas.getContext('2d');
  this.sourceDimensions = {};
  this.dimensions = HorizonLine.dimensions;
  this.sourceXPos = [this.spritePos.x, this.spritePos.x +
      this.dimensions.WIDTH];
  this.xPos = [];
  this.yPos = 0;
  this.bumpThreshold = 0.5;

  this.setSourceDimensions();
  this.draw();
};


/**
 * Horizon line dimensions.
 * @enum {number}
 */
HorizonLine.dimensions = {
  WIDTH: 600,
  HEIGHT: 12,
  YPOS: 127
};


HorizonLine.prototype = {
  /**
   * Set the source dimensions of the horizon line.
   */
  setSourceDimensions: function() {

    for (var dimension in HorizonLine.dimensions) {
      if (IS_HIDPI) {
        if (dimension != 'YPOS') {
          this.sourceDimensions[dimension] =
              HorizonLine.dimensions[dimension] * 2;
        }
      } else {
        this.sourceDimensions[dimension] =
            HorizonLine.dimensions[dimension];
      }
      this.dimensions[dimension] = HorizonLine.dimensions[dimension];
    }

    this.xPos = [0, HorizonLine.dimensions.WIDTH];
    this.yPos = HorizonLine.dimensions.YPOS;
  },

  /**
   * Return the crop x position of a type.
   */
  getRandomType: function() {
    return Math.random() > this.bumpThreshold ? this.dimensions.WIDTH : 0;
  },

  /**
   * Draw the horizon line.
   */
  draw: function() {
    this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[0],
        this.spritePos.y,
        this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
        this.xPos[0], this.yPos,
        this.dimensions.WIDTH, this.dimensions.HEIGHT);

    this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[1],
        this.spritePos.y,
        this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
        this.xPos[1], this.yPos,
        this.dimensions.WIDTH, this.dimensions.HEIGHT);
  },

  /**
   * Update the x position of an indivdual piece of the line.
   * @param {number} pos Line position.
   * @param {number} increment
   */
  updateXPos: function(pos, increment) {
    var line1 = pos;
    var line2 = pos == 0 ? 1 : 0;

    this.xPos[line1] -= increment;
    this.xPos[line2] = this.xPos[line1] + this.dimensions.WIDTH;

    if (this.xPos[line1] <= -this.dimensions.WIDTH) {
      this.xPos[line1] += this.dimensions.WIDTH * 2;
      this.xPos[line2] = this.xPos[line1] - this.dimensions.WIDTH;
      this.sourceXPos[line1] = this.getRandomType() + this.spritePos.x;
    }
  },

  /**
   * Update the horizon line.
   * @param {number} deltaTime
   * @param {number} speed
   */
  update: function(deltaTime, speed) {
    var increment = Math.floor(speed * (FPS / 1000) * deltaTime);

    if (this.xPos[0] <= 0) {
      this.updateXPos(0, increment);
    } else {
      this.updateXPos(1, increment);
    }
    this.draw();
  },

  /**
   * Reset horizon to the starting position.
   */
  reset: function() {
    this.xPos[0] = 0;
    this.xPos[1] = HorizonLine.dimensions.WIDTH;
  }
};


//******************************************************************************

/**
 * Horizon background class.
 * @param {HTMLCanvasElement} canvas
 * @param {Object} spritePos Sprite positioning.
 * @param {Object} dimensions Canvas dimensions.
 * @param {number} gapCoefficient
 * @constructor
 */
function Horizon(canvas, spritePos, dimensions, gapCoefficient) {
  this.canvas = canvas;
  this.canvasCtx = this.canvas.getContext('2d');
  this.config = Horizon.config;
  this.dimensions = dimensions;
  this.gapCoefficient = gapCoefficient;
  this.obstacles = [];
  this.obstacleHistory = [];
  this.horizonOffsets = [0, 0];
  this.cloudFrequency = this.config.CLOUD_FREQUENCY;
  this.spritePos = spritePos;
  this.nightMode = null;

  // Cloud
  this.clouds = [];
  this.cloudSpeed = this.config.BG_CLOUD_SPEED;

  // Horizon
  this.horizonLine = null;
  this.init();
};


/**
 * Horizon config.
 * @enum {number}
 */
Horizon.config = {
  BG_CLOUD_SPEED: 0.2,
  BUMPY_THRESHOLD: .3,
  CLOUD_FREQUENCY: .5,
  HORIZON_HEIGHT: 16,
  MAX_CLOUDS: 6
};


Horizon.prototype = {
  /**
   * Initialise the horizon. Just add the line and a cloud. No obstacles.
   */
  init: function() {
    this.addCloud();
    this.horizonLine = new HorizonLine(this.canvas, this.spritePos.HORIZON);
    this.nightMode = new NightMode(this.canvas, this.spritePos.MOON,
        this.dimensions.WIDTH);
  },

  /**
   * @param {number} deltaTime
   * @param {number} currentSpeed
   * @param {boolean} updateObstacles Used as an override to prevent
   *     the obstacles from being updated / added. This happens in the
   *     ease in section.
   * @param {boolean} showNightMode Night mode activated.
   */
  update: function(deltaTime, currentSpeed, updateObstacles, showNightMode) {
    this.runningTime += deltaTime;
    this.horizonLine.update(deltaTime, currentSpeed);
    this.nightMode.update(showNightMode);
    this.updateClouds(deltaTime, currentSpeed);

    if (updateObstacles) {
      this.updateObstacles(deltaTime, currentSpeed);
    }
  },

  /**
   * Update the cloud positions.
   * @param {number} deltaTime
   * @param {number} currentSpeed
   */
  updateClouds: function(deltaTime, speed) {
    var cloudSpeed = this.cloudSpeed / 1000 * deltaTime * speed;
    var numClouds = this.clouds.length;

    if (numClouds) {
      for (var i = numClouds - 1; i >= 0; i--) {
        this.clouds[i].update(cloudSpeed);
      }

      var lastCloud = this.clouds[numClouds - 1];

      // Check for adding a new cloud.
      if (numClouds < this.config.MAX_CLOUDS &&
          (this.dimensions.WIDTH - lastCloud.xPos) > lastCloud.cloudGap &&
          this.cloudFrequency > Math.random()) {
        this.addCloud();
      }

      // Remove expired clouds.
      this.clouds = this.clouds.filter(function(obj) {
        return !obj.remove;
      });
    } else {
      this.addCloud();
    }
  },

  /**
   * Update the obstacle positions.
   * @param {number} deltaTime
   * @param {number} currentSpeed
   */
  updateObstacles: function(deltaTime, currentSpeed) {
    // Obstacles, move to Horizon layer.
    var updatedObstacles = this.obstacles.slice(0);

    for (var i = 0; i < this.obstacles.length; i++) {
      var obstacle = this.obstacles[i];
      obstacle.update(deltaTime, currentSpeed);

      // Clean up existing obstacles.
      if (obstacle.remove) {
        updatedObstacles.shift();
      }
    }
    this.obstacles = updatedObstacles;

    if (this.obstacles.length > 0) {
      var lastObstacle = this.obstacles[this.obstacles.length - 1];

      if (lastObstacle && !lastObstacle.followingObstacleCreated &&
          lastObstacle.isVisible() &&
          (lastObstacle.xPos + lastObstacle.width + lastObstacle.gap) <
          this.dimensions.WIDTH) {
        this.addNewObstacle(currentSpeed);
        lastObstacle.followingObstacleCreated = true;
      }
    } else {
      // Create new obstacles.
      this.addNewObstacle(currentSpeed);
    }
  },

  removeFirstObstacle: function() {
    this.obstacles.shift();
  },

  /**
   * Add a new obstacle.
   * @param {number} currentSpeed
   */
  addNewObstacle: function(currentSpeed) {
    var obstacleTypeIndex = getRandomNum(0, Obstacle.types.length - 1);
    var obstacleType = Obstacle.types[obstacleTypeIndex];

    // Check for multiples of the same type of obstacle.
    // Also check obstacle is available at current speed.
    if (this.duplicateObstacleCheck(obstacleType.type) ||
        currentSpeed < obstacleType.minSpeed) {
      this.addNewObstacle(currentSpeed);
    } else {
      var obstacleSpritePos = this.spritePos[obstacleType.type];

      this.obstacles.push(new Obstacle(this.canvasCtx, obstacleType,
          obstacleSpritePos, this.dimensions,
          this.gapCoefficient, currentSpeed, obstacleType.width));

      this.obstacleHistory.unshift(obstacleType.type);

      if (this.obstacleHistory.length > 1) {
        this.obstacleHistory.splice(Runner.config.MAX_OBSTACLE_DUPLICATION);
      }
    }
  },

  /**
   * Returns whether the previous two obstacles are the same as the next one.
   * Maximum duplication is set in config value MAX_OBSTACLE_DUPLICATION.
   * @return {boolean}
   */
  duplicateObstacleCheck: function(nextObstacleType) {
    var duplicateCount = 0;

    for (var i = 0; i < this.obstacleHistory.length; i++) {
      duplicateCount = this.obstacleHistory[i] == nextObstacleType ?
          duplicateCount + 1 : 0;
    }
    return duplicateCount >= Runner.config.MAX_OBSTACLE_DUPLICATION;
  },

  /**
   * Reset the horizon layer.
   * Remove existing obstacles and reposition the horizon line.
   */
  reset: function() {
    this.obstacles = [];
    this.horizonLine.reset();
    this.nightMode.reset();
  },

  /**
   * Update the canvas width and scaling.
   * @param {number} width Canvas width.
   * @param {number} height Canvas height.
   */
  resize: function(width, height) {
    this.canvas.width = width;
    this.canvas.height = height;
  },

  /**
   * Add a new cloud to the horizon.
   */
  addCloud: function() {
    this.clouds.push(new Cloud(this.canvas, this.spritePos.CLOUD,
        this.dimensions.WIDTH));
  }
};
})();
</script>
</head>
<body id="t" i18n-values=".style.fontFamily:fontfamily;.style.fontSize:fontsize" jstcache="0" class="neterror" style="font-family: system-ui, &quot;PingFang SC&quot;, STHeiti, sans-serif; font-size: 75%;">
  <div id="main-frame-error" class="interstitial-wrapper" jstcache="0">
    <div id="main-content" jstcache="0">
      <div class="icon icon-generic" jseval="updateIconClass(this.classList, iconClass)" alt="" jstcache="1"></div>
      <div id="main-message" jstcache="0">
        <h1 jsselect="heading" jsvalues=".innerHTML:msg" jstcache="5"><span jscontent="hostName" jstcache="16">log.51cto.com</span> 已被屏蔽</h1>
        <p jsselect="summary" jsvalues=".innerHTML:msg" jstcache="2">对服务器的请求已遭到某个扩展程序的阻止。</p>
        <div id="suggestions-list" jsdisplay="(suggestionsSummaryList &amp;&amp; suggestionsSummaryList.length)" jstcache="6">
          <p jsvalues=".innerHTML:suggestionsSummaryListHeader" jstcache="13"></p>
          <ul jsvalues=".className:suggestionsSummaryList.length == 1 ? &#39;single-suggestion&#39; : &#39;&#39;" jstcache="14" class="single-suggestion">
            <li jsselect="suggestionsSummaryList" jsvalues=".innerHTML:summary" jstcache="15" jsinstance="*0">尝试停用扩展程序。</li>
          </ul>
        </div>
        <div class="error-code" jscontent="errorCode" jstcache="7">ERR_BLOCKED_BY_CLIENT</div>
        <div id="diagnose-frame" class="hidden" jstcache="0"></div>
      </div>
    </div>
    <div id="buttons" class="nav-wrapper suggested-right" jstcache="0">
      <div id="control-buttons" jstcache="0">
        
        <button id="reload-button" class="blue-button text-button" onclick="trackClick(this.trackingId);
                     reloadButtonClick(this.url);" jsselect="reloadButton" jsvalues=".url:reloadUrl; .trackingId:reloadTrackingId" jscontent="msg" jstcache="8">重新加载</button><button id="show-saved-copy-button" class="blue-button text-button" onclick="showSavedCopyButtonClick()" jsselect="showSavedCopyButton" jscontent="msg" jsvalues="title:title; .primary:primary" jstcache="9" style="display: none;">
        </button>
        <button id="download-button" class="blue-button text-button" onclick="downloadButtonClick()" jsselect="downloadButton" jscontent="msg" jsvalues=".disabledText:disabledMsg" jstcache="10" style="display: none;">
        </button>
      </div>
      <button id="details-button" class="text-button small-link" onclick="detailsButtonClick(); toggleHelpBox()" jscontent="details" jsdisplay="(suggestionsDetails &amp;&amp; suggestionsDetails.length &gt; 0) || diagnose" jsvalues=".detailsText:details; .hideDetailsText:hideDetails;" jstcache="3" style="display: none;"></button>
    </div>
    <div id="details" class="hidden" jstcache="0">
      <div class="suggestions" jsselect="suggestionsDetails" jstcache="4" jsinstance="*0" style="display: none;">
        <div class="suggestion-header" jsvalues=".innerHTML:header" jstcache="11"></div>
        <div class="suggestion-body" jsvalues=".innerHTML:body" jstcache="12"></div>
      </div>
    </div>
  </div>
  <div id="sub-frame-error" jstcache="0">
    <!-- Show details when hovering over the icon, in case the details are
         hidden because they're too large. -->
    <div class="icon icon-generic" jseval="updateIconClass(this.classList, iconClass)" jstcache="1"></div>
    <div id="sub-frame-error-details" jsselect="summary" jsvalues=".innerHTML:msg" jstcache="2">对服务器的请求已遭到某个扩展程序的阻止。</div>
  </div>

  <div id="offline-resources" jstcache="0">
    <img id="offline-resources-1x" src="" jstcache="0">
    <img id="offline-resources-2x" src="" jstcache="0">
    <template id="audio-resources" jstcache="0"></template>
  </div>


<script jstcache="0">// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview This file defines a singleton which provides access to all data
 * that is available as soon as the page's resources are loaded (before DOM
 * content has finished loading). This data includes both localized strings and
 * any data that is important to have ready from a very early stage (e.g. things
 * that must be displayed right away).
 */

/** @type {!LoadTimeData} */ var loadTimeData;

// Expose this type globally as a temporary work around until
// https://github.com/google/closure-compiler/issues/544 is fixed.
/** @constructor */
function LoadTimeData(){}

(function() {
  'use strict';

  LoadTimeData.prototype = {
    /**
     * Sets the backing object.
     *
     * Note that there is no getter for |data_| to discourage abuse of the form:
     *
     *     var value = loadTimeData.data()['key'];
     *
     * @param {Object} value The de-serialized page data.
     */
    set data(value) {
      expect(!this.data_, 'Re-setting data.');
      this.data_ = value;
    },

    /**
     * Returns a JsEvalContext for |data_|.
     * @returns {JsEvalContext}
     */
    createJsEvalContext: function() {
      return new JsEvalContext(this.data_);
    },

    /**
     * @param {string} id An ID of a value that might exist.
     * @return {boolean} True if |id| is a key in the dictionary.
     */
    valueExists: function(id) {
      return id in this.data_;
    },

    /**
     * Fetches a value, expecting that it exists.
     * @param {string} id The key that identifies the desired value.
     * @return {*} The corresponding value.
     */
    getValue: function(id) {
      expect(this.data_, 'No data. Did you remember to include strings.js?');
      var value = this.data_[id];
      expect(typeof value != 'undefined', 'Could not find value for ' + id);
      return value;
    },

    /**
     * As above, but also makes sure that the value is a string.
     * @param {string} id The key that identifies the desired string.
     * @return {string} The corresponding string value.
     */
    getString: function(id) {
      var value = this.getValue(id);
      expectIsType(id, value, 'string');
      return /** @type {string} */ (value);
    },

    /**
     * Returns a formatted localized string where $1 to $9 are replaced by the
     * second to the tenth argument.
     * @param {string} id The ID of the string we want.
     * @param {...(string|number)} var_args The extra values to include in the
     *     formatted output.
     * @return {string} The formatted string.
     */
    getStringF: function(id, var_args) {
      var value = this.getString(id);
      if (!value)
        return '';

      var varArgs = arguments;
      return value.replace(/\$[$1-9]/g, function(m) {
        return m == '$$' ? '$' : varArgs[m[1]];
      });
    },

    /**
     * As above, but also makes sure that the value is a boolean.
     * @param {string} id The key that identifies the desired boolean.
     * @return {boolean} The corresponding boolean value.
     */
    getBoolean: function(id) {
      var value = this.getValue(id);
      expectIsType(id, value, 'boolean');
      return /** @type {boolean} */ (value);
    },

    /**
     * As above, but also makes sure that the value is an integer.
     * @param {string} id The key that identifies the desired number.
     * @return {number} The corresponding number value.
     */
    getInteger: function(id) {
      var value = this.getValue(id);
      expectIsType(id, value, 'number');
      expect(value == Math.floor(value), 'Number isn\'t integer: ' + value);
      return /** @type {number} */ (value);
    },

    /**
     * Override values in loadTimeData with the values found in |replacements|.
     * @param {Object} replacements The dictionary object of keys to replace.
     */
    overrideValues: function(replacements) {
      expect(
          typeof replacements == 'object',
          'Replacements must be a dictionary object.');
      for (var key in replacements) {
        this.data_[key] = replacements[key];
      }
    }
  };

  /**
   * Checks condition, displays error message if expectation fails.
   * @param {*} condition The condition to check for truthiness.
   * @param {string} message The message to display if the check fails.
   */
  function expect(condition, message) {
    if (!condition) {
      console.error(
          'Unexpected condition on ' + document.location.href + ': ' + message);
    }
  }

  /**
   * Checks that the given value has the given type.
   * @param {string} id The id of the value (only used for error message).
   * @param {*} value The value to check the type on.
   * @param {string} type The type we expect |value| to be.
   */
  function expectIsType(id, value, type) {
    expect(
        typeof value == type, '[' + value + '] (' + id + ') is not a ' + type);
  }

  expect(!loadTimeData, 'should only include this file once');
  loadTimeData = new LoadTimeData;
})();
</script><script jstcache="0">loadTimeData.data = {"details":"详细信息","errorCode":"ERR_BLOCKED_BY_CLIENT","fontfamily":"system-ui,PingFang SC,STHeiti,sans-serif","fontsize":"75%","heading":{"hostName":"log.51cto.com","msg":"\u003Cspan jscontent=\"hostName\">\u003C/span> 已被屏蔽"},"hideDetails":"隐藏详细信息","iconClass":"icon-generic","language":"zh","reloadButton":{"msg":"重新加载","reloadTrackingId":-1,"reloadUrl":"http://log.51cto.com/pageview.php?frompos=blog_art"},"suggestionsDetails":[],"suggestionsSummaryList":[{"summary":"尝试停用扩展程序。"}],"summary":{"dnsDefinition":"DNS 是一项网络服务，可将网站的名称转译为其对应的互联网地址。","failedUrl":"http://log.51cto.com/pageview.php?frompos=blog_art","hostName":"log.51cto.com","msg":"对服务器的请求已遭到某个扩展程序的阻止。"},"textdirection":"ltr","title":"log.51cto.com"};</script><script jstcache="0">// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Note: vulcanize sometimes disables GRIT processing. If you're importing i18n
// stuff with <link rel="import">, you should probably be using
// html/i18n_template.html instead of this file.

// // Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/** @typedef {Document|DocumentFragment|Element} */
var ProcessingRoot;

/**
 * @fileoverview This is a simple template engine inspired by JsTemplates
 * optimized for i18n.
 *
 * It currently supports three handlers:
 *
 *   * i18n-content which sets the textContent of the element.
 *
 *     <span i18n-content="myContent"></span>
 *
 *   * i18n-options which generates <option> elements for a <select>.
 *
 *     <select i18n-options="myOptionList"></select>
 *
 *   * i18n-values is a list of attribute-value or property-value pairs.
 *     Properties are prefixed with a '.' and can contain nested properties.
 *
 *     <span i18n-values="title:myTitle;.style.fontSize:fontSize"></span>
 *
 * This file is a copy of i18n_template.js, with minor tweaks to support using
 * load_time_data.js. It should replace i18n_template.js eventually.
 */

var i18nTemplate = (function() {
  /**
   * This provides the handlers for the templating engine. The key is used as
   * the attribute name and the value is the function that gets called for every
   * single node that has this attribute.
   * @type {!Object}
   */
  var handlers = {
    /**
     * This handler sets the textContent of the element.
     * @param {!HTMLElement} element The node to modify.
     * @param {string} key The name of the value in |data|.
     * @param {!LoadTimeData} data The data source to draw from.
     * @param {!Set<ProcessingRoot>} visited
     */
    'i18n-content': function(element, key, data, visited) {
      element.textContent = data.getString(key);
    },

    /**
     * This handler adds options to a <select> element.
     * @param {!HTMLElement} select The node to modify.
     * @param {string} key The name of the value in |data|. It should
     *     identify an array of values to initialize an <option>. Each value,
     *     if a pair, represents [content, value]. Otherwise, it should be a
     *     content string with no value.
     * @param {!LoadTimeData} data The data source to draw from.
     * @param {!Set<ProcessingRoot>} visited
     */
    'i18n-options': function(select, key, data, visited) {
      var options = data.getValue(key);
      options.forEach(function(optionData) {
        var option = typeof optionData == 'string' ?
            new Option(optionData) :
            new Option(optionData[1], optionData[0]);
        select.appendChild(option);
      });
    },

    /**
     * This is used to set HTML attributes and DOM properties. The syntax is:
     *   attributename:key;
     *   .domProperty:key;
     *   .nested.dom.property:key
     * @param {!HTMLElement} element The node to modify.
     * @param {string} attributeAndKeys The path of the attribute to modify
     *     followed by a colon, and the name of the value in |data|.
     *     Multiple attribute/key pairs may be separated by semicolons.
     * @param {!LoadTimeData} data The data source to draw from.
     * @param {!Set<ProcessingRoot>} visited
     */
    'i18n-values': function(element, attributeAndKeys, data, visited) {
      var parts = attributeAndKeys.replace(/\s/g, '').split(/;/);
      parts.forEach(function(part) {
        if (!part)
          return;

        var attributeAndKeyPair = part.match(/^([^:]+):(.+)$/);
        if (!attributeAndKeyPair)
          throw new Error('malformed i18n-values: ' + attributeAndKeys);

        var propName = attributeAndKeyPair[1];
        var propExpr = attributeAndKeyPair[2];

        var value = data.getValue(propExpr);

        // Allow a property of the form '.foo.bar' to assign a value into
        // element.foo.bar.
        if (propName[0] == '.') {
          var path = propName.slice(1).split('.');
          var targetObject = element;
          while (targetObject && path.length > 1) {
            targetObject = targetObject[path.shift()];
          }
          if (targetObject) {
            targetObject[path] = value;
            // In case we set innerHTML (ignoring others) we need to recursively
            // check the content.
            if (path == 'innerHTML') {
              for (var i = 0; i < element.children.length; ++i) {
                processWithoutCycles(element.children[i], data, visited, false);
              }
            }
          }
        } else {
          element.setAttribute(propName, /** @type {string} */ (value));
        }
      });
    }
  };

  var prefixes = [''];

  // Only look through shadow DOM when it's supported. As of April 2015, iOS
  // Chrome doesn't support shadow DOM.
  if (Element.prototype.createShadowRoot)
    prefixes.push('* /deep/ ');

  var attributeNames = Object.keys(handlers);
  var selector = prefixes
                     .map(function(prefix) {
                       return prefix + '[' +
                           attributeNames.join('], ' + prefix + '[') + ']';
                     })
                     .join(', ');

  /**
   * Processes a DOM tree using a |data| source to populate template values.
   * @param {!ProcessingRoot} root The root of the DOM tree to process.
   * @param {!LoadTimeData} data The data to draw from.
   */
  function process(root, data) {
    processWithoutCycles(root, data, new Set(), true);
  }

  /**
   * Internal process() method that stops cycles while processing.
   * @param {!ProcessingRoot} root
   * @param {!LoadTimeData} data
   * @param {!Set<ProcessingRoot>} visited Already visited roots.
   * @param {boolean} mark Whether nodes should be marked processed.
   */
  function processWithoutCycles(root, data, visited, mark) {
    if (visited.has(root)) {
      // Found a cycle. Stop it.
      return;
    }

    // Mark the node as visited before recursing.
    visited.add(root);

    var importLinks = root.querySelectorAll('link[rel=import]');
    for (var i = 0; i < importLinks.length; ++i) {
      var importLink = /** @type {!HTMLLinkElement} */ (importLinks[i]);
      if (!importLink.import) {
        // Happens when a <link rel=import> is inside a <template>.
        // TODO(dbeam): should we log an error if we detect that here?
        continue;
      }
      processWithoutCycles(importLink.import, data, visited, mark);
    }

    var templates = root.querySelectorAll('template');
    for (var i = 0; i < templates.length; ++i) {
      var template = /** @type {HTMLTemplateElement} */ (templates[i]);
      if (!template.content)
        continue;
      processWithoutCycles(template.content, data, visited, mark);
    }

    var isElement = root instanceof Element;
    if (isElement && root.webkitMatchesSelector(selector))
      processElement(/** @type {!Element} */ (root), data, visited);

    var elements = root.querySelectorAll(selector);
    for (var i = 0; i < elements.length; ++i) {
      processElement(elements[i], data, visited);
    }

    if (mark) {
      var processed = isElement ? [root] : root.children;
      if (processed) {
        for (var i = 0; i < processed.length; ++i) {
          processed[i].setAttribute('i18n-processed', '');
        }
      }
    }
  }

  /**
   * Run through various [i18n-*] attributes and populate.
   * @param {!Element} element
   * @param {!LoadTimeData} data
   * @param {!Set<ProcessingRoot>} visited
   */
  function processElement(element, data, visited) {
    for (var i = 0; i < attributeNames.length; i++) {
      var name = attributeNames[i];
      var attribute = element.getAttribute(name);
      if (attribute != null)
        handlers[name](element, attribute, data, visited);
    }
  }

  return {process: process};
}());

// // Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

i18nTemplate.process(document, loadTimeData);

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// Use of this source code is governed by a BSD-style license that can be
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})()
// clang-format on
</script><script jstcache="0">var tp = document.getElementById('t');jstProcess(loadTimeData.createJsEvalContext(), tp);</script></body></html>